Stabilisation quick fixes: orderly close, visible version and update band, chat pop-ups on, Windows shaders and hwdec, render logs

- Close: hide the window, dispose every player, thumbnail job and the
  sound engine, leave, then close normally; Linux runner _exit (the
  NVIDIA EGL exit handler crashed 10/10 closes, 0/41 now); Windows tears
  down inside the message loop, then TerminateProcess; watchdogs.
- Version under the Settings tab; an update band instead of a dot,
  never over a video; checks at start and every 4 hours.
- Chat pop-ups default to All again.
- Shader read-back compared as a list (old mpv joins with ','), so
  Windows stops turning shaders off; Windows hwdec auto-copy.
- Render diagnostics (`mpv: render` lines); RAM-only demuxer cache pin
  silences the file-cache warning; a volume readout test.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/test/shaders_mpv_test.dart

@@ -27,9 +27,9 @@ void main() {
       s.setShaderPreset(ShaderPreset.a);
       await p.init();
       final dynamic mpv = p.player.platform;
-      final modeA = joinShaderPaths(
-          await shaderPathsFor(ShaderPreset.a, ShaderQuality.hq, const []));
-      expect(await mpv.getProperty('glsl-shaders'), modeA);
+      final modeA =
+          await shaderPathsFor(ShaderPreset.a, ShaderQuality.hq, const []);
+      expect(shaderListMatches(modeA, await mpv.getProperty('glsl-shaders')), isTrue);
       expect(p.shaderNotice.value, isNull);
 
       // Live change, announced.
@@ -39,7 +39,7 @@ void main() {
       final caFast = await shaderPathsFor(
           ShaderPreset.ca, ShaderQuality.fast, const []);
       expect(caFast.first, startsWith(support.path));
-      expect(await mpv.getProperty('glsl-shaders'), joinShaderPaths(caFast));
+      expect(shaderListMatches(caFast, await mpv.getProperty('glsl-shaders')), isTrue);
       expect(p.shaderNotice.value?.text, 'Shaders: Mode C+A (Fast)');
 
       // A missing custom file: toast, off, nothing set.