feat(rah-light): remove voice features

- Delete voice hooks: useVoiceSession, useRealtimeVoiceClient, useAssistantTTS, useVoiceInterruption
- Delete voice API routes: /api/voice/tts, /api/realtime/ephemeral-token
- Delete voice service: src/services/voice/usageLogger.ts
- Clean up RAHChat.tsx: remove voice stub hooks and voice-related state/handlers
- Clean up TerminalInput.tsx: remove voice props, mic icons, amplitude visualizer

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

ralph/prd.json

@@ -13,8 +13,8 @@
         "No remaining imports of 'delegation' from services/agents",
         "npm run type-check passes"
       ],
-      "passes": false,
-      "notes": ""
+      "passes": true,
+      "notes": "Replaced AgentDelegationService with direct execution in workflowExecutor and quickAdd. Added stub AgentDelegation types and voice hook stubs to UI components for compatibility (to be removed in later stories)."
     },
     {
       "id": "2",
@@ -31,8 +31,8 @@
         "RAHChat.tsx no longer imports or uses voice hooks",
         "npm run type-check passes"
       ],
-      "passes": false,
-      "notes": ""
+      "passes": true,
+      "notes": "Deleted all 4 voice hooks, voice API routes (/api/voice/, /api/realtime/), voice service directory. Removed voice stub hooks and voice-related code from RAHChat.tsx and TerminalInput.tsx."
     },
     {
       "id": "3",