feat(stats): add Hide Kana filter and fix vocabulary exclusion matching

- Remove overlay mining image toast; OSD card notifications no longer flash a frame screenshot
- Add Hide Kana toggle to frequency rank table to filter kana-only headwords
- Fix vocab exclusions to deduplicate and match token variants (e.g. ない / 無い) under one exclusion entry
- Skip cover image fetching when the overview tab is inactive

src/anki-integration.test.ts

@@ -406,47 +406,6 @@ test('AnkiIntegration marks partial update notifications as failures in OSD mode
   assert.deepEqual(osdMessages, ['x Updated card: taberu (image failed)']);
 });
 
-test('AnkiIntegration emits a mining image data URL to the overlay for OSD notifications', async () => {
-  const osdMessages: string[] = [];
-  const overlayImages: string[] = [];
-  const integration = new AnkiIntegration(
-    {
-      behavior: {
-        notificationType: 'osd',
-      },
-    },
-    {} as never,
-    { currentVideoPath: '/tmp/video.mkv', currentTimePos: 12 } as never,
-    (text) => {
-      osdMessages.push(text);
-    },
-  );
-  integration.setMiningImageOverlayCallback((image) => {
-    overlayImages.push(image);
-  });
-
-  const internals = integration as unknown as {
-    mediaGenerator: {
-      generateNotificationIcon: (path: string, timestamp: number) => Promise<Buffer>;
-    };
-    showNotification: (
-      noteId: number,
-      label: string | number,
-      errorSuffix?: string,
-    ) => Promise<void>;
-  };
-  internals.mediaGenerator = {
-    generateNotificationIcon: async () => Buffer.from('frame-bytes'),
-  } as never;
-
-  await internals.showNotification(7, 'taberu');
-
-  assert.deepEqual(osdMessages, ['✓ Updated card: taberu']);
-  assert.deepEqual(overlayImages, [
-    `data:image/png;base64,${Buffer.from('frame-bytes').toString('base64')}`,
-  ]);
-});
-
 test('FieldGroupingMergeCollaborator keeps SentenceAudio grouped without overwriting ExpressionAudio', async () => {
   const collaborator = createFieldGroupingMergeCollaborator();