fix: address texture watchdog/probe review findings

- watchdog: compare the plugin's cumulative consumed counter against a
  snapshot taken when arming (re-arm was a no-op before), and judge on
  cumulative pushes + elapsed time so sparse damage-driven streams are
  still detected
- failure handling is idempotent (one record per breakage) and updates
  every render session like main_set_local_option does, not only the
  failing one; the fallback toast is not claimed for multi-display
  windows the soft path cannot rescue
- probe: skip when the consumed API is missing (old plugin) or a
  raster-stall is recorded (compositing could hang the main window);
  a fail verdict requires fresh frame timings and a non-minimized
  window; a pass never clears failed-raster-stall; toast only when
  texture rendering was effectively on; probe pixel is transparent
- raster-stall monitor: judge on frame-timing staleness (a mid-episode
  hang was undetectable before), gate on lifecycle/minimized/idle with
  a moving quiet anchor, threshold 30s, shared with the camera page;
  clear stateGlobal minimized flag on plain window restore
- adopt mismatched frame sizes only in multi-ui-session mode (legacy
  mode pairs frames loosely and could ping-pong between displays)
- drop the now-dead closeSession parameter from texture destroy();
  trim comments to repo style

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

flutter/lib/desktop/pages/remote_page.dart

@@ -21,6 +21,7 @@ import '../../common/shared_state.dart';
 import '../../utils/image.dart';
 import '../widgets/remote_toolbar.dart';
 import '../widgets/kb_layout_type_chooser.dart';
+import '../widgets/raster_stall_monitor.dart';
 import '../widgets/tabbar_widget.dart';
 import 'macos_full_screen_focus_recovery.dart';
 
@@ -156,7 +157,7 @@ class _RemotePageState extends State<RemotePage>
           widget.tabController?.state.listen(_onMacOSTabStateChanged);
     }
     Get.put<FFI>(_ffi, tag: widget.id);
-    _RasterStallMonitor.start();
+    RasterStallMonitor.start();
     _ffi.imageModel.addCallbackOnFirstImage((String peerId) {
       _ffi.canvasModel.activateLocalCursor();
       showKBLayoutTypeChooserIfNeeded(
@@ -648,7 +649,7 @@ class _RemotePageState extends State<RemotePage>
     // Clear callback reference to prevent memory leaks and stale references
     _ffi.inputModel.onRelativeMouseModeDisabled = null;
     // Relative mouse mode cleanup is centralized in FFI.close(closeSession: ...).
-    _ffi.textureModel.onRemotePageDispose(closeSession);
+    _ffi.textureModel.onRemotePageDispose();
     if (closeSession && !isMacOS) {
       // ensure we leave this session, this is a double check
       // enterOrLeave() is already called previously in _releaseMacOSRemoteInput() for macOS.
@@ -1404,44 +1405,3 @@ class CursorPaint extends StatelessWidget {
   }
 }
 
-/// Detects a hung raster thread: the UI keeps scheduling frames but the
-/// engine never reports completed frame timings. Rendering cannot be rescued
-/// in-process (software rendering needs the same raster thread), so this only
-/// records the breakage — the next launch then defaults texture rendering to
-/// off and the startup probe re-validates the environment.
-class _RasterStallMonitor {
-  static bool _started = false;
-  static bool _reported = false;
-  static DateTime? _lastTimings;
-  static DateTime? _scheduledSince;
-
-  static void start() {
-    if (_started || isWeb) return;
-    _started = true;
-    SchedulerBinding.instance.addTimingsCallback((_) {
-      _lastTimings = DateTime.now();
-    });
-    Timer.periodic(const Duration(seconds: 2), (_) {
-      if (_reported) return;
-      // A minimized window legitimately stops producing frame timings.
-      if (stateGlobal.isMinimized ||
-          !SchedulerBinding.instance.hasScheduledFrame) {
-        _scheduledSince = null;
-        return;
-      }
-      final now = DateTime.now();
-      _scheduledSince ??= now;
-      final lastTimings = _lastTimings;
-      final stalled =
-          now.difference(_scheduledSince!) > const Duration(seconds: 10) &&
-              (lastTimings == null || lastTimings.isBefore(_scheduledSince!));
-      if (stalled) {
-        _reported = true;
-        bind.mainSetLocalOption(
-            key: kOptionTextureRenderHealth, value: 'failed-raster-stall');
-        debugPrint(
-            'raster thread stall detected, texture rendering disabled for next launch');
-      }
-    });
-  }
-}

flutter/lib/desktop/pages/view_camera_page.dart

@@ -19,6 +19,7 @@ import '../../common/shared_state.dart';
 import '../../utils/image.dart';
 import '../widgets/remote_toolbar.dart';
 import '../widgets/kb_layout_type_chooser.dart';
+import '../widgets/raster_stall_monitor.dart';
 import '../widgets/tabbar_widget.dart';
 
 import 'package:flutter_hbb/native/custom_cursor.dart'
@@ -102,6 +103,7 @@ class _ViewCameraPageState extends State<ViewCameraPage>
     super.initState();
     _ffi = FFI(widget.sessionId);
     Get.put<FFI>(_ffi, tag: widget.id);
+    RasterStallMonitor.start();
     _ffi.imageModel.addCallbackOnFirstImage((String peerId) {
       showKBLayoutTypeChooserIfNeeded(
           _ffi.ffiModel.pi.platform, _ffi.dialogManager);
@@ -222,7 +224,7 @@ class _ViewCameraPageState extends State<ViewCameraPage>
     // https://github.com/flutter/flutter/issues/64935
     super.dispose();
     debugPrint("VIEW CAMERA PAGE dispose session $sessionId ${widget.id}");
-    _ffi.textureModel.onViewCameraPageDispose(closeSession);
+    _ffi.textureModel.onViewCameraPageDispose();
     if (closeSession) {
       // ensure we leave this session, this is a double check
       _ffi.inputModel.enterOrLeave(false);