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/runtime.ts

@@ -1,10 +1,6 @@
 import { DEFAULT_ANKI_CONNECT_CONFIG } from '../config';
 import type { AnkiConnectConfig } from '../types/anki';
-import {
-  getKnownWordCacheLifecycleConfig,
-  getKnownWordCacheRefreshIntervalMinutes,
-  getKnownWordCacheScopeForConfig,
-} from './known-word-cache';
+import { getKnownWordCacheLifecycleConfig } from './known-word-cache';
 
 export interface AnkiIntegrationRuntimeProxyServer {
   start(options: { host: string; port: number; upstreamUrl: string }): void;
@@ -255,14 +251,6 @@ export class AnkiIntegrationRuntime {
     return getKnownWordCacheLifecycleConfig(config);
   }
 
-  private getKnownWordRefreshIntervalMinutes(config: AnkiConnectConfig): number {
-    return getKnownWordCacheRefreshIntervalMinutes(config);
-  }
-
-  private getKnownWordCacheScopeForConfig(config: AnkiConnectConfig): string {
-    return getKnownWordCacheScopeForConfig(config);
-  }
-
   getOrCreateProxyServer(): AnkiIntegrationRuntimeProxyServer {
     if (!this.proxyServer) {
       this.proxyServer = this.deps.proxyServerFactory();