Improve startup dictionary sync UX and default playback keybindings

- Add default `f` fullscreen overlay binding and switch default AniSkip skip key to `Tab`
- Make character-dictionary auto-sync non-blocking at startup with tokenization gating for Yomitan mutations
- Add ordered startup OSD progress (checking/generating/updating/importing), refresh current subtitle on sync completion, and extend regression tests

src/config/definitions/domain-registry.test.ts

@@ -73,3 +73,10 @@ test('default keybindings include primary and secondary subtitle track cycling o
   assert.deepEqual(keybindingMap.get('KeyJ'), ['cycle', 'sid']);
   assert.deepEqual(keybindingMap.get('Shift+KeyJ'), ['cycle', 'secondary-sid']);
 });
+
+test('default keybindings include fullscreen on F', () => {
+  const keybindingMap = new Map(
+    DEFAULT_KEYBINDINGS.map((binding) => [binding.key, binding.command]),
+  );
+  assert.deepEqual(keybindingMap.get('KeyF'), ['cycle', 'fullscreen']);
+});

src/config/definitions/shared.ts

@@ -50,6 +50,7 @@ export const SPECIAL_COMMANDS = {
 
 export const DEFAULT_KEYBINDINGS: NonNullable<ResolvedConfig['keybindings']> = [
   { key: 'Space', command: ['cycle', 'pause'] },
+  { key: 'KeyF', command: ['cycle', 'fullscreen'] },
   { key: 'KeyJ', command: ['cycle', 'sid'] },
   { key: 'Shift+KeyJ', command: ['cycle', 'secondary-sid'] },
   { key: 'ArrowRight', command: ['seek', 5] },