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/linux/runner/main.cc

@@ -1,6 +1,16 @@
+#include <stdio.h>
+#include <unistd.h>
+
 #include "my_application.h"
 
 int main(int argc, char** argv) {
-  g_autoptr(MyApplication) app = my_application_new();
-  return g_application_run(G_APPLICATION(app), argc, argv);
+  MyApplication* app = my_application_new();
+  int status = g_application_run(G_APPLICATION(app), argc, argv);
+  // The window is gone and the engine with it (the app disposed its mpv
+  // players and left before closing the window). Skip exit(): its handlers
+  // include NVIDIA's EGL teardown (libEGL_nvidia), which segfaults inside
+  // exit() for Flutter apps. Nothing is left to flush but stdio.
+  fflush(stdout);
+  fflush(stderr);
+  _exit(status);
 }