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

src/core/services/tokenizer/annotation-stage.ts

@@ -390,23 +390,6 @@ function isReduplicatedKanaSfx(text: string): boolean {
   return chars.slice(0, half).join('') === chars.slice(half).join('');
 }
 
-function isReduplicatedKanaSfxWithOptionalTrailingTo(text: string): boolean {
-  const normalized = normalizeKana(text);
-  if (!normalized) {
-    return false;
-  }
-
-  if (isReduplicatedKanaSfx(normalized)) {
-    return true;
-  }
-
-  if (normalized.length <= 1 || !normalized.endsWith('と')) {
-    return false;
-  }
-
-  return isReduplicatedKanaSfx(normalized.slice(0, -1));
-}
-
 function hasAdjacentKanaRepeat(text: string): boolean {
   const normalized = normalizeKana(text);
   if (!normalized) {