feat(input): opt-in WebKitGTK focus repaint workaround for Linux (#342, #782) (#884)

* feat(input): opt-in WebKitGTK focus repaint workaround for Linux (#342, #782)

Some Linux users on WebKitGTK 2.50.x report a freeze when clicking
text fields: the field receives focus (right-click paste still works)
but the canvas never redraws until the window is resized. Likely a
layer-flush / composition scheduling bug in 2.50.x's Skia rendering
pipeline.

Off by default. When enabled in Settings -> System -> Behavior, every
input/textarea focus triggers a sync reflow read plus a one-frame
translateZ(0) toggle on the input's parent so WebKit re-evaluates the
layer tree. Side-effect: search-icon siblings flicker briefly on
focus -- accepted trade-off, only paid by users who opt in.

The toggle row is gated on IS_LINUX and sits next to the existing
Linux WebKitGTK options. The effect subscribes to the auth store and
re-attaches the focusin handler whenever the flag flips, so toggling
off cleanly removes the listener.

* i18n(settings): linux input repaint toggle in all locales

Adds linuxWebkitInputForceRepaint label + description across en, de,
fr, es, nl, nb, ro, zh, ru.

* docs(release): CHANGELOG and credits for linux input freeze workaround (PR #884)

src/app/AppShell.tsx

@@ -164,6 +164,32 @@ export function AppShell() {
     return () => window.removeEventListener('psy:toggle-sidebar', onToggleSidebar);
   }, [isSidebarCollapsed, setSidebarCollapsed]);
 
+  // Workaround for WebKitGTK 2.50.x text-input repaint hang on
+  // Linux Mint / Ubuntu 24.04 (issues #342, #782). When opted in,
+  // nudge WebKit awake on every input/textarea focus via a sync
+  // reflow read plus a one-frame translateZ(0) toggle on the input's
+  // parent so the rendering pipeline re-evaluates the layer tree.
+  // Side-effect: search magnifier flickers briefly on focus.
+  const linuxWebkitInputForceRepaint = useAuthStore(s => s.linuxWebkitInputForceRepaint);
+  useEffect(() => {
+    if (!linuxWebkitInputForceRepaint) return;
+    const handler = (e: FocusEvent) => {
+      const target = e.target;
+      if (!(target instanceof HTMLElement)) return;
+      const tag = target.tagName;
+      if (tag !== 'INPUT' && tag !== 'TEXTAREA') return;
+      const layerHost = (target.parentElement as HTMLElement | null) ?? target;
+      void layerHost.offsetHeight;
+      const previous = layerHost.style.transform;
+      layerHost.style.transform = 'translateZ(0)';
+      requestAnimationFrame(() => {
+        layerHost.style.transform = previous;
+      });
+    };
+    document.addEventListener('focusin', handler, true);
+    return () => document.removeEventListener('focusin', handler, true);
+  }, [linuxWebkitInputForceRepaint]);
+
   const {
     queueWidth,
     isDraggingQueue,