fix: make locale-independence real, not assumed — parsing, casing, comparison

Follow-up to the retail-text fix. "Green under sv-SE" is not the same as "runs
on any locale", so this establishes the latter by running the suite under
cultures chosen to break different things, and fixing what they broke.

ar-SA found a genuine defect the Swedish runner cannot see: the resolution
parser read "1920x-1" through the ambient culture, and ar-SA's negative sign is
not ASCII '-', so the parse failed and the height silently became 0 instead of
-1. Both copies of that parser (App settings targets and the UI settings store)
now parse invariantly.

Audited every remaining culture-sensitive operation in src/ rather than fixing
only what a test happened to catch:

- Numeric Parse/TryParse with no IFormatProvider: 11 sites, all reading
  MACHINE-readable input — env vars (ACDREAM_LIGHT_DEBUG, ACDREAM_NET_DROP_*,
  streaming/quality knobs), CLI arguments, "1920x1080" settings keys, a chat
  command's price argument, and the launcher's bake thread count, which is
  handed straight to a child process command line. All pinned to
  InvariantCulture.
- ToUpper()/ToLower() with no culture: none. The Turkish-I class was already
  clean, and tr-TR confirms it.
- StartsWith/EndsWith/IndexOf(string) with no StringComparison: one —
  ChatInputParser's "@" prefix test, which is a culture-sensitive comparison
  for a single ASCII character. Now the ordinal char overload.

Verified: 13,958 tests pass identically under the machine default, sv-SE,
tr-TR, ar-SA, and de-DE. (The two launcher test assemblies are excluded from
this run only because a running acdream-launcher.exe holds its own binary; the
one launcher change here is the thread-count parse.)

Dates remain on the current culture by intent, unchanged from the previous
commit.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/AcDream.App/Rendering/DisplayModeCatalog.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System;
 using System.Collections.Generic;
 using System.Linq;
@@ -134,8 +135,10 @@ internal static class DisplayModeCatalog
             mode = default;
             string[] parts = spec.Split('x', 2);
             if (parts.Length == 2
-                && int.TryParse(parts[0], out int w)
-                && int.TryParse(parts[1], out int h)
+                && int.TryParse(
+                    parts[0], NumberStyles.Integer, CultureInfo.InvariantCulture, out int w)
+                && int.TryParse(
+                    parts[1], NumberStyles.Integer, CultureInfo.InvariantCulture, out int h)
                 && w > 0
                 && h > 0)
             {

src/AcDream.App/Settings/RuntimeSettingsTargets.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Linq;
 using AcDream.App.Audio;
 using AcDream.App.Net;
@@ -206,9 +207,14 @@ internal sealed class SilkRuntimeDisplayWindowTarget : IRuntimeDisplayWindowTarg
         if (string.IsNullOrWhiteSpace(spec))
             return false;
         string[] parts = spec.Split('x', 2);
+        // Invariant: a resolution spec is a machine-readable settings key, not
+        // localized input. Parsing it with the ambient culture made "1920x-1"
+        // fail outright under ar-SA, whose negative sign is not ASCII "-".
         return parts.Length == 2
-            && int.TryParse(parts[0], out width)
-            && int.TryParse(parts[1], out height)
+            && int.TryParse(
+                parts[0], NumberStyles.Integer, CultureInfo.InvariantCulture, out width)
+            && int.TryParse(
+                parts[1], NumberStyles.Integer, CultureInfo.InvariantCulture, out height)
             && width > 0
             && height > 0;
     }

src/AcDream.App/Streaming/StreamingDiagnostics.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System;
 
 namespace AcDream.App.Streaming;
@@ -73,5 +74,8 @@ internal static class StreamingDiagnostics
     /// at the parser rather than let the two halves of one commit disagree.
     /// </summary>
     internal static int? ParseRadius(string? raw) =>
-        int.TryParse(raw, out int value) && value >= 1 ? value : null;
+        int.TryParse(raw, NumberStyles.Integer, CultureInfo.InvariantCulture, out int value)
+        && value >= 1
+            ? value
+            : null;
 }

src/AcDream.App/UI/ClientCommandController.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using AcDream.Core.Physics;
 using AcDream.Core.Ui;
 using AcDream.Core.Social;
@@ -724,7 +725,8 @@ public sealed class ClientCommandController
         uint maximumPrice = 0u;
         foreach (string part in parts)
         {
-            if (uint.TryParse(part, out uint price))
+            if (uint.TryParse(
+                    part, NumberStyles.Integer, CultureInfo.InvariantCulture, out uint price))
             {
                 if (price == 0)
                 {

src/AcDream.Cli/Program.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.Diagnostics;
 using AcDream.Cli;
 using DatReaderWriter;
@@ -96,7 +97,7 @@ if (args.Length >= 1 && args[0] == "probe")
 {
     // probe <in.png> <x0> <y0> <x1> <y1>
     if (args.Length < 6) { Console.Error.WriteLine("usage: AcDream.Cli probe <in.png> <x0> <y0> <x1> <y1>"); return 2; }
-    return VitalsMockup.Probe(args[1], int.Parse(args[2]), int.Parse(args[3]), int.Parse(args[4]), int.Parse(args[5]));
+    return VitalsMockup.Probe(args[1], int.Parse(args[2], CultureInfo.InvariantCulture), int.Parse(args[3], CultureInfo.InvariantCulture), int.Parse(args[4], CultureInfo.InvariantCulture), int.Parse(args[5], CultureInfo.InvariantCulture));
 }
 
 if (args.Length >= 1 && args[0] == "crop")
@@ -104,7 +105,7 @@ if (args.Length >= 1 && args[0] == "crop")
     // crop <in.png> <x> <y> <w> <h> <zoom> <out.png>
     if (args.Length < 8) { Console.Error.WriteLine("usage: AcDream.Cli crop <in.png> <x> <y> <w> <h> <zoom> <out.png>"); return 2; }
     return VitalsMockup.Crop(args[1],
-        int.Parse(args[2]), int.Parse(args[3]), int.Parse(args[4]), int.Parse(args[5]), int.Parse(args[6]), args[7]);
+        int.Parse(args[2], CultureInfo.InvariantCulture), int.Parse(args[3], CultureInfo.InvariantCulture), int.Parse(args[4], CultureInfo.InvariantCulture), int.Parse(args[5], CultureInfo.InvariantCulture), int.Parse(args[6], CultureInfo.InvariantCulture), args[7]);
 }
 
 if (args.Length >= 1 && args[0] == "dump-edges")

src/AcDream.Core.Net/NetDiagnostics.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 namespace AcDream.Core.Net;
 
 /// <summary>
@@ -74,6 +75,8 @@ public static class NetDiagnostics
     public static int NetDropSeed { get; set; } =
         int.TryParse(
             Environment.GetEnvironmentVariable("ACDREAM_NET_DROP_SEED"),
+            NumberStyles.Integer,
+            CultureInfo.InvariantCulture,
             out int seed)
             ? seed
             : 1;
@@ -87,7 +90,8 @@ public static class NetDiagnostics
             Environment.GetEnvironmentVariable("ACDREAM_NET_DROP_DIR"));
 
     internal static int ParseDropPercent(string? value) =>
-        int.TryParse(value, out int percent) && percent is >= 0 and <= 100
+        int.TryParse(value, NumberStyles.Integer, CultureInfo.InvariantCulture, out int percent)
+        && percent is >= 0 and <= 100
             ? percent
             : 0;
 

src/AcDream.Core/Rendering/RenderingDiagnostics.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System;
 using System.Collections.Generic;
 using System.Text;
@@ -355,7 +356,13 @@ public static class RenderingDiagnostics
     /// future DebugPanel mirror.
     /// </summary>
     public static int LightDebugMode { get; set; } =
-        int.TryParse(Environment.GetEnvironmentVariable("ACDREAM_LIGHT_DEBUG"), out var ldm) ? ldm : 0;
+        int.TryParse(
+            Environment.GetEnvironmentVariable("ACDREAM_LIGHT_DEBUG"),
+            NumberStyles.Integer,
+            CultureInfo.InvariantCulture,
+            out int ldm)
+            ? ldm
+            : 0;
 
     /// <summary>
     /// #176 stripe-hunt isolation (<c>ACDREAM_CLIP_DEBUG=1</c>) — throwaway

src/AcDream.Launcher/ViewModels/FirstRunInstallerViewModel.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System.ComponentModel;
 using AcDream.Launcher.Core.Installation;
 using AcDream.Launcher.Core.Launching;
@@ -90,7 +91,9 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
     }
 
     public bool IsThreadCountValid =>
-        int.TryParse(ThreadsText, out int threads) && threads > 0;
+        int.TryParse(
+            ThreadsText, NumberStyles.Integer, CultureInfo.InvariantCulture, out int threads)
+        && threads > 0;
 
     public string ThreadCountValidation => IsThreadCountValid
         ? "Worker count is valid."
@@ -324,7 +327,12 @@ public sealed class FirstRunInstallerViewModel : ObservableObject, IDisposable
 
     private async Task StartAsync()
     {
-        if (!int.TryParse(ThreadsText, out int threads) || threads <= 0)
+        if (!int.TryParse(
+                ThreadsText,
+                NumberStyles.Integer,
+                CultureInfo.InvariantCulture,
+                out int threads)
+            || threads <= 0)
         {
             return;
         }

src/AcDream.Runtime/Chat/ChatInputParser.cs

@@ -213,7 +213,7 @@ public static class ChatInputParser
         // (e.g. @acehelp, @tele, @die), pass the literal @-prefixed
         // text through to the default channel so ACE's CommandManager
         // server-side handler intercepts it.
-        if (trimmed.StartsWith("@"))
+        if (trimmed.StartsWith('@'))
         {
             string substituted = "/" + trimmed.Substring(1);
             string verb = ExtractVerb(substituted);

src/AcDream.UI.Abstractions/Panels/Settings/SettingsStore.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using System;
 using System.Collections.Generic;
 using System.IO;
@@ -632,8 +633,16 @@ public sealed class SettingsStore
         height = 0;
         int separator = key.IndexOf('x', StringComparison.OrdinalIgnoreCase);
         return separator > 0
-            && int.TryParse(key.AsSpan(0, separator), out width)
-            && int.TryParse(key.AsSpan(separator + 1), out height)
+            && int.TryParse(
+                key.AsSpan(0, separator),
+                NumberStyles.Integer,
+                CultureInfo.InvariantCulture,
+                out width)
+            && int.TryParse(
+                key.AsSpan(separator + 1),
+                NumberStyles.Integer,
+                CultureInfo.InvariantCulture,
+                out height)
             && width > 0
             && height > 0;
     }

src/AcDream.UI.Abstractions/Settings/QualityPreset.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 namespace AcDream.UI.Abstractions.Settings;
 
 /// <summary>
@@ -62,6 +63,9 @@ public readonly record struct QualitySettings(
     private static int TryParseEnvInt(string name, int defaultValue)
     {
         var s = System.Environment.GetEnvironmentVariable(name);
-        return s is not null && int.TryParse(s, out var v) ? v : defaultValue;
+        return s is not null
+            && int.TryParse(s, NumberStyles.Integer, CultureInfo.InvariantCulture, out int v)
+                ? v
+                : defaultValue;
     }
 }