fix(ci): make launcher space guidance culture invariant

src/AcDream.Launcher.Core/Installation/LauncherInstaller.cs

@@ -1,6 +1,7 @@
 using AcDream.Launcher.Core.Integrity;
 using AcDream.Launcher.Core.Launching;
 using AcDream.Platform;
+using System.Globalization;
 
 namespace AcDream.Launcher.Core.Installation;
 
@@ -326,9 +327,9 @@ public sealed class LauncherInstaller : ILauncherInstaller
         {
             string message =
                 $"The optimized world-data rebuild needs at least "
-                + $"{FullRebuildRequiredFreeBytes / (1024d * 1024d * 1024d):N1} GiB free "
+                + $"{FormatGiB(FullRebuildRequiredFreeBytes)} GiB free "
                 + $"beside the active package; only "
-                + $"{availableBytes / (1024d * 1024d * 1024d):N1} GiB is available.";
+                + $"{FormatGiB(availableBytes)} GiB is available.";
             Report(progress, LauncherInstallPhase.Failed, message);
             throw new LauncherInstallException(message);
         }
@@ -636,6 +637,9 @@ public sealed class LauncherInstaller : ILauncherInstaller
             .ConfigureAwait(false);
     }
 
+    private static string FormatGiB(long bytes) =>
+        (bytes / (1024d * 1024d * 1024d)).ToString("N1", CultureInfo.InvariantCulture);
+
     public async Task<LauncherInstallResult> ApplyContentUpdateAsync(
         string datDirectory,
         int threads,