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

tests/test_ws_hub.py

@@ -0,0 +1,74 @@
+"""Quick test for WebSocket Hub connection and auth protocol."""
+import asyncio
+import json
+import os
+import urllib.request
+from dotenv import load_dotenv
+
+load_dotenv()
+
+
+async def test_ws():
+    import websockets
+
+    reg_code = os.getenv("GRAVITY_REGISTRATION_CODE")
+    uri = "ws://localhost:8586/ws"
+
+    print(f"1. Connecting to {uri}...")
+    async with websockets.connect(uri) as ws:
+        # Correct auth protocol: type=auth with registration_code
+        auth_msg = {
+            "type": "auth",
+            "registration_code": reg_code,
+            "project": "gravity_control",
+            "pc": "test_pc",
+        }
+        await ws.send(json.dumps(auth_msg))
+        print("2. Sent auth message")
+
+        resp = await asyncio.wait_for(ws.recv(), timeout=5)
+        resp_data = json.loads(resp)
+        print(f"3. Auth response: {json.dumps(resp_data, indent=2)}")
+
+        if resp_data.get("type") == "auth_ok":
+            print("4. AUTH SUCCESS!")
+            conn_id = resp_data.get("conn_id", "")
+            instance = resp_data.get("instance_number", "")
+            print(f"   conn_id={conn_id}, instance=#{instance}")
+
+            # Send a chat message (Hub expects type='chat', not 'chat_snapshot')
+            snap = {
+                "type": "chat",
+                "data": {
+                    "content": "[TEST] Hub WS test message",
+                    "project_name": "gravity_control",
+                    "conversation_id": "test-ws-hub-123",
+                },
+            }
+            await ws.send(json.dumps(snap))
+            print("5. Sent chat_snapshot via WS")
+
+            # Check hub status via HTTP
+            r = urllib.request.urlopen("http://localhost:8586/hub/status", timeout=3)
+            status = json.loads(r.read())
+            print(f"6. Hub status: {json.dumps(status, indent=2)}")
+
+            # Send register message
+            reg = {
+                "type": "register",
+                "conversation_id": "test-ws-hub-123",
+                "project_name": "gravity_control",
+            }
+            await ws.send(json.dumps(reg))
+            print("7. Sent register")
+
+        else:
+            reason = resp_data.get("reason", "unknown")
+            print(f"4. AUTH FAILED: {reason}")
+
+        await ws.close()
+        print("8. Done!")
+
+
+if __name__ == "__main__":
+    asyncio.run(test_ws())