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

changes/remove-dead-code-docs.md

@@ -0,0 +1,4 @@
+type: docs
+area: launcher
+
+- Removed `SUBMINER_JIMAKU_API_KEY`, `SUBMINER_JIMAKU_API_KEY_COMMAND`, and `SUBMINER_JIMAKU_API_BASE_URL` from the development docs' environment variable table. The launcher never used them; set the Jimaku key with `jimaku.apiKey` / `jimaku.apiKeyCommand` in the config instead.