fix: retail text and golden-string tests must not follow the machine's locale

Run 170's Windows gate went red on 37 tests across four assemblies while the
same commit passed 14,370/0 locally. The failures were all one family:

  Expected: "You have 1 500p"     <- built with the machine's culture
  Actual:   "You have 1,500p"     <- production, correctly invariant

The runner is Swedish; this dev box is not. These tests had been passing on CI
only because that machine's registry locale had been pinned by hand — machine
state, which came undone (almost certainly the reboot after today's hang).
Re-pinning it would be a workaround on one machine for a defect in the repo,
so this fixes the repo instead.

Two genuinely different bugs were hiding in that one symptom.

1. TESTS that build an expected string with the ambient culture and compare it
   to invariant production output, and test-side recording sinks whose traces
   are compared against literal golden strings. Those only ever passed on a
   machine that happens to format like the invariant culture. Pinned to
   InvariantCulture: the vendor purse/cost expectations, and the motion-funnel,
   animation-sequencer, framebuffer-resize, resource-slot, and runtime-attack
   trace sinks.

2. PRODUCTION that formats player-visible retail text with the ambient culture.
   This one matters beyond CI: retail is a US client, so it shows "2.50",
   "1,500p" and "(-20)" to everyone. On a Swedish machine acdream was showing
   "2,50", "1 500p" and "(-20)" with U+2212 MINUS SIGN — the audience for this
   alpha is literally Swedish. Converted 76 sites to InvariantCulture across the
   item/creature appraisal formatters, the character stat panel's buff and vitae
   parentheticals, the appraisal and link-status controllers, the chat
   /framerate and /location output, the camera sensitivity toast, the
   time-override toast, the F3 dump, the sky diagnostics, and the world-frame
   invariant-failure message.

   DATES are deliberately left on the current culture (CharacterController's
   birth/login stamp, RuntimeHouseState's purchase expiry). Retail has no answer
   for a non-US player's date format, and forcing "08/19/2026 7:00:00 PM" on
   them is a UX decision, not a retail-fidelity one.

Apparatus, so the next occurrence is reproducible instead of mysterious:
tests/TestCultureInitializer.cs adds an opt-in ACDREAM_TEST_CULTURE knob to
every test assembly, linked in through a new tests/Directory.Build.props.
Unset — what CI and everyone runs — it changes nothing.

  ACDREAM_TEST_CULTURE=sv-SE dotnet test ...

reproduced all 37 CI failures on this machine plus 6 more the runner's own
locale does not surface (the Unicode-minus family), and drove the fix.

Verified both ways on the full solution under the release-gate filter:
default culture 14,370 passed / 0 failed, and ACDREAM_TEST_CULTURE=sv-SE
14,370 passed / 0 failed.

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

tests/AcDream.App.Tests/Rendering/FramebufferResizeControllerTests.cs

@@ -1,3 +1,4 @@
+using System.Globalization;
 using AcDream.App.Input;
 using AcDream.App.Rendering;
 
@@ -81,7 +82,9 @@ public sealed class FramebufferResizeControllerTests
 
     private sealed class Camera(List<string> calls) : IFramebufferCameraTarget
     {
-        public void SetAspect(float aspect) => calls.Add($"camera:{aspect:F3}");
+        public void SetAspect(float aspect) => calls.Add(
+            // Invariant: compared against literal golden strings.
+            string.Create(CultureInfo.InvariantCulture, $"camera:{aspect:F3}"));
     }
 
     private sealed class DevTools(List<string> calls) : IFramebufferDevToolsTarget