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/core/services/immersion-tracker/__tests__/query.test.ts

@@ -2769,7 +2769,6 @@ test('getSessionWordsByLine joins word occurrences through imm_words.id', () =>
 
   try {
     ensureSchema(db);
-    const stmts = createTrackerPreparedStatements(db);
     const startedAtMs = 1_735_732_800_000;
     const videoId = getOrCreateVideoRecord(db, '/tmp/session-words-by-line.mkv', {
       canonicalTitle: 'Episode',

src/core/services/immersion-tracker/query-library.ts

@@ -18,7 +18,6 @@ import type {
 } from './types';
 import {
   ACTIVE_SESSION_METRICS_CTE,
-  SESSION_WORD_COUNTS_CTE,
   SESSION_WORD_COUNTS_SELECT,
   fromDbTimestamp,
   resolvedCoverBlobExpr,

src/core/services/immersion-tracker/query-maintenance.ts

@@ -16,7 +16,6 @@ import { deriveStoredPartOfSpeech } from '../tokenizer/part-of-speech';
 import {
   cleanupUnusedCoverArtBlobHash,
   findSharedCoverBlobHash,
-  toDbMs,
   toDbTimestamp,
 } from './query-shared';
 

src/core/services/immersion-tracker/storage.ts

@@ -9,7 +9,7 @@ import { ensureLexicalDailyRollupTables, markLexicalDailyRollupsReady } from './
 import { isVocabularyStatsRowVisible, type VocabularyVisibilityRow } from './vocabulary-visibility';
 import { SCHEMA_VERSION } from './types';
 import type { QueuedWrite, VideoMetadata, YoutubeVideoMetadata } from './types';
-import { toDbMs, toDbTimestamp } from './query-shared';
+import { toDbTimestamp } from './query-shared';
 
 export interface TrackerPreparedStatements {
   telemetryInsertStmt: ReturnType<DatabaseSync['prepare']>;