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/youtube-subgen-config.ts

@@ -16,31 +16,9 @@ export function parseLauncherYoutubeSubgenConfig(
     secondarySubRaw && typeof secondarySubRaw === 'object'
       ? (secondarySubRaw as Record<string, unknown>)
       : null;
-  const jimakuRaw = root.jimaku;
-  const jimaku =
-    jimakuRaw && typeof jimakuRaw === 'object' ? (jimakuRaw as Record<string, unknown>) : null;
-
-  const jimakuLanguagePreference = jimaku?.languagePreference;
-  const jimakuMaxEntryResults = jimaku?.maxEntryResults;
 
   return {
     primarySubLanguages: asStringArray(youtube?.primarySubLanguages),
     secondarySubLanguages: asStringArray(secondarySub?.secondarySubLanguages),
-    jimakuApiKey: typeof jimaku?.apiKey === 'string' ? jimaku.apiKey : undefined,
-    jimakuApiKeyCommand:
-      typeof jimaku?.apiKeyCommand === 'string' ? jimaku.apiKeyCommand : undefined,
-    jimakuApiBaseUrl: typeof jimaku?.apiBaseUrl === 'string' ? jimaku.apiBaseUrl : undefined,
-    jimakuLanguagePreference:
-      jimakuLanguagePreference === 'ja' ||
-      jimakuLanguagePreference === 'en' ||
-      jimakuLanguagePreference === 'none'
-        ? jimakuLanguagePreference
-        : undefined,
-    jimakuMaxEntryResults:
-      typeof jimakuMaxEntryResults === 'number' &&
-      Number.isFinite(jimakuMaxEntryResults) &&
-      jimakuMaxEntryResults > 0
-        ? Math.floor(jimakuMaxEntryResults)
-        : undefined,
   };
 }