refactor: remove dead code and enable noUnusedLocals (#292)

* refactor: remove dead code and enable noUnusedLocals

- delete launcher/jimaku.ts and the launcher Args/config jimaku* fields
  that only fed it (the SUBMINER_JIMAKU_* env vars had no effect)
- delete plugin/subminer/hover.lua; nothing has sent subminer-hover-token
  since Overlay 2.0
- drop never-read anilist.characterDictionary.refreshTtlHours and
  evictionPolicy (still hidden in the settings UI for old configs)
- drop unused root deps: eslint, @fontsource-variable/geist{,-mono}
  (stats/ declares its own)
- delete the committed draft renderer-performance plan doc
- turn on noUnusedLocals for typecheck and remove what it surfaced,
  including Windows focus-handoff values computed but never consumed

* docs(changes): add docs fragment and note retired hover messages

launcher/config-domain-parsers.test.ts

@@ -17,20 +17,11 @@ test('parseLauncherYoutubeSubgenConfig keeps only valid typed values', () => {
     secondarySub: {
       secondarySubLanguages: ['eng', true, 'deu'],
     },
-    jimaku: {
-      apiKey: 'abc',
-      apiKeyCommand: 'pass show key',
-      apiBaseUrl: 'https://jimaku.cc',
-      languagePreference: 'ja',
-      maxEntryResults: 8.7,
-    },
   });
 
   assert.equal('mode' in parsed, false);
   assert.deepEqual(parsed.primarySubLanguages, ['ja', 'en']);
   assert.deepEqual(parsed.secondarySubLanguages, ['eng', 'deu']);
-  assert.equal(parsed.jimakuLanguagePreference, 'ja');
-  assert.equal(parsed.jimakuMaxEntryResults, 8);
 });
 
 test('parseLauncherJellyfinConfig omits legacy token and user id fields', () => {