Initial scaffold: FastAPI backend + Vue 3 frontend + Docker setup

Backend: config/db/security/logging core, SQLAlchemy models (Server,
Credential, UpdateJob, UpdateLog, AuditLog, User), services (winrm, ssh,
cau, audit, job_runner), REST API (auth, servers, updates, audit),
Socket.io WebSocket layer.
Frontend: Vue 3 + TS + Pinia + Tailwind, Views (Dashboard, Servers,
Updates, Audit, Login), axios + socket.io-client, nginx prod config.

backend/app/websocket/manager.py

@@ -0,0 +1,43 @@
+"""Connection manager for Socket.io rooms (one room per update job)."""
+
+from app.core.logging import get_logger
+
+logger = get_logger(__name__)
+
+
+class WSManager:
+    """Tracks active Socket.io sessions and job-room subscriptions."""
+
+    def __init__(self) -> None:
+        # sid -> set of job rooms the client subscribed to
+        self._subscriptions: dict[str, set[str]] = {}
+
+    def register(self, sid: str) -> None:
+        self._subscriptions.setdefault(sid, set())
+        logger.info("ws.client_connected", sid=sid)
+
+    def unregister(self, sid: str) -> None:
+        self._subscriptions.pop(sid, None)
+        logger.info("ws.client_disconnected", sid=sid)
+
+    def subscribe(self, sid: str, job_id: int) -> str:
+        room = self.room_for(job_id)
+        self._subscriptions.setdefault(sid, set()).add(room)
+        return room
+
+    def unsubscribe(self, sid: str, job_id: int) -> str:
+        room = self.room_for(job_id)
+        if sid in self._subscriptions:
+            self._subscriptions[sid].discard(room)
+        return room
+
+    @staticmethod
+    def room_for(job_id: int) -> str:
+        return f"job:{job_id}"
+
+    @property
+    def client_count(self) -> int:
+        return len(self._subscriptions)
+
+
+ws_manager = WSManager()