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/anki-integration.ts

@@ -41,7 +41,6 @@ import type { NPlusOneMatchMode, SubtitleMiningContext } from './types/subtitle'
 import { DEFAULT_ANKI_CONNECT_CONFIG } from './config';
 import {
   getConfiguredWordFieldCandidates,
-  getConfiguredWordFieldName,
   getPreferredWordValueFromExtractedFields,
 } from './anki-field-config';
 import { createLogger } from './logger';
@@ -1632,10 +1631,6 @@ export class AnkiIntegration {
     return sentenceCardConfig.audioField || 'SentenceAudio';
   }
 
-  private getConfiguredWordFieldName(): string {
-    return getConfiguredWordFieldName(this.config);
-  }
-
   private getConfiguredWordFieldCandidates(): string[] {
     return getConfiguredWordFieldCandidates(this.config);
   }