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/commands/mpv-command.ts

@@ -65,7 +65,7 @@ export async function runMpvPostAppCommand(
   context: LauncherCommandContext,
   deps: MpvCommandDeps = defaultDeps,
 ): Promise<boolean> {
-  const { args, appPath, scriptPath, mpvSocketPath, pluginRuntimeConfig } = context;
+  const { args, appPath, mpvSocketPath, pluginRuntimeConfig } = context;
   if (!args.mpvIdle) {
     return false;
   }