chore(tui): /clean recent perf work — KISS/DRY pass

24 files, -319 LoC. Behaviour preserved, 369/369 tests green.

- hermes-ink caches: shared lruEvict helper for the four parallel LRU
  caches (stringWidth, wrapText, sliceAnsi, lineWidth); touch-on-read
  stays inlined per cache; tightened output.ts skip-slice fast path.
- wheelAccel: trimmed provenance header, collapsed env parsing, ternary
  dispatch in computeWheelStep.
- perfPane: folded ensureLogDir into once-flag, spread-with-overrides
  for fastPath/phases instead of full rebuilds.
- env: extracted truthy() (used 4×).
- virtualHeights: collapsed user/diff/slash height bumps; trail+todos
  estimate.
- useInputHandlers: scrollIdleTimer cleanup on unmount, ?? undefined
  shorthand.
- useMainApp: dropped dead liveTailVisible IIFE and liveProgress
  indirection.
- appLayout, markdown, messageLine, entry: vertical rhythm, dropped
  narration comments, inlined one-shot vars.
- fix: empty catch blocks → /* best-effort */ for no-empty lint.

ui-tui/src/lib/liveProgress.test.ts

@@ -104,7 +104,10 @@ describe('appendToolShelfMessage', () => {
 
   it('starts a new shelf across assistant text boundaries', () => {
     const merged = appendToolShelfMessage(
-      [{ kind: 'trail', role: 'system', text: '', tools: ['one ✓'] }, { role: 'assistant', text: 'done' }],
+      [
+        { kind: 'trail', role: 'system', text: '', tools: ['one ✓'] },
+        { role: 'assistant', text: 'done' }
+      ],
       { kind: 'trail', role: 'system', text: '', tools: ['two ✓'] }
     )