feat: voice command mapping — context-gated approve/reject over voice

While a tool-permission gate is held on the active tab, spoken confirm
phrases resolve it via the existing approve/reject WS channel — no server
change (byte-shuttle intact). Everything else stays ordinary dictation.

Safety: whole-utterance-exact matching + leading-negation guard + reject
precedence + confidence gate (approve only) + a cancellable 1.5s confirm
window whose commit re-validates gate identity/epoch/connectivity (TOCTOU
guard) + stale-gate epoch bound at PTT-start.

New pure modules public/voice-commands.ts and public/voice-confirm.ts at
100% coverage; wiring in voice/terminal-session/tabs/main. 1307 tests pass,
typecheck clean, build:web OK. Independent code + security reviews flagged a
confirm-window TOCTOU and an unwired cancel path — both fixed and covered.

Plan: docs/PLAN_VOICE_COMMANDS.md.

vitest.config.ts

@@ -22,6 +22,8 @@ export default defineConfig({
         'public/tabs.ts',
         'public/preview-grid.ts',
         'public/title-util.ts',
+        'public/voice-commands.ts',
+        'public/voice-confirm.ts',
       ],
       thresholds: {
         lines: 80,