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

plugin/subminer/state.lua

@@ -8,16 +8,6 @@ function M.new()
 		binary_available = false,
 		binary_path = nil,
 		detected_backend = nil,
-		hover_highlight = {
-			revision = -1,
-			payload = nil,
-			saved_sub_visibility = nil,
-			saved_secondary_sub_visibility = nil,
-			overlay_active = false,
-			cached_ass = nil,
-			clear_timer = nil,
-			last_hover_update_ts = 0,
-		},
 		auto_play_ready_gate_armed = false,
 		auto_play_ready_should_resume_playback = false,
 		auto_play_ready_timeout = nil,