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/immersion-tracker/query-library.ts

@@ -18,7 +18,6 @@ import type {
 } from './types';
 import {
   ACTIVE_SESSION_METRICS_CTE,
-  SESSION_WORD_COUNTS_CTE,
   SESSION_WORD_COUNTS_SELECT,
   fromDbTimestamp,
   resolvedCoverBlobExpr,