refactor(extension): 모듈 분리 + Hub 통합 테스트 #task-395

- extension.ts 3,446→1,289줄 (-63%)
- step-probe.ts (1,435줄): setupMonitor, processResponseFile, tryApprovalStrategies
- observer-script.ts (687줄): DOM observer script
- ws-client.ts (390줄): WSBridgeClient
- step-utils.ts (114줄): step 파싱 유틸
- auth.py (115줄): JWT + registration code
- hub.py (581줄): WSHub + per-client queue
- Hub WS 연동 테스트 통과 (auth, chat, register)
- VSIX v0.4.0 빌드

main.py

@@ -102,14 +102,29 @@ async def main():
         else:
             logger.info("Gateway mode — watcher disabled (data via HTTP API)")
 
-        # Start Gateway HTTP API (gateway mode)
+        # Start Gateway HTTP API + WebSocket Hub (gateway mode)
         if Config.BOT_MODE == 'gateway':
             from gateway import GatewayAPI
+            from hub import WSHub
+            from auth import TokenManager
+
+            # Initialize Hub
+            token_mgr = TokenManager(
+                secret=Config.GRAVITY_HUB_SECRET,
+                registration_code=Config.GRAVITY_REGISTRATION_CODE,
+            )
+            hub = WSHub(token_mgr)
+
             gateway_port = int(os.environ.get('GATEWAY_PORT', '8585'))
-            gateway = GatewayAPI(bot, port=gateway_port, api_key=Config.GATEWAY_API_KEY)
+            gateway = GatewayAPI(
+                bot, port=gateway_port,
+                api_key=Config.GATEWAY_API_KEY,
+                hub=hub,
+            )
             bot.gateway = gateway  # Enable _write_command → gateway.push_command
+            bot.hub = hub          # Enable Hub-based message routing
             await gateway.start()
-            logger.info(f"Gateway API running on port {gateway_port}")
+            logger.info(f"Gateway API + WS Hub running on port {gateway_port}")
 
         # Run Discord bot (blocks until bot disconnects)
         await bot.start(Config.DISCORD_TOKEN)