Phase 11: remote UX & network attach (0.11.0)

- Live remote-stack logs over a WebSocket proxied through the central app to
  the agent (/ws/agent-logs/{agent}/{stack}); agent gains a WS log endpoint.
- Deploy to a remote host from the UI: host selector in the New Stack editor
  and template dialog; templates instantiate onto an agent via the proxy.
- Network attach/detach: expandable inspect view per network with
  connect/disconnect + container picker; GET /{id}/containers, POST connect/disconnect.
- Remove dead pages/Placeholder.tsx.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

backend/routers/networks.py

@@ -36,6 +36,12 @@ class NetworkCreate(BaseModel):
     attachable: bool = True
 
 
+class ContainerRef(BaseModel):
+    container: str
+    aliases: list[str] | None = None
+    force: bool = False
+
+
 @router.get("")
 def list_networks(_user: User = Depends(get_current_user)) -> list[dict]:
     return network_service.list_networks()
@@ -43,7 +49,58 @@ def list_networks(_user: User = Depends(get_current_user)) -> list[dict]:
 
 @router.get("/{network_id}")
 def inspect_network(network_id: str, _user: User = Depends(get_current_user)) -> dict:
-    return network_service.inspect_network(network_id)
+    try:
+        return network_service.inspect_network(network_id)
+    except DockerError as exc:
+        _map(exc)
+
+
+@router.get("/{network_id}/containers")
+def network_containers(
+    network_id: str, _user: User = Depends(get_current_user)
+) -> list[dict]:
+    try:
+        return network_service.connectable_containers(network_id)
+    except DockerError as exc:
+        _map(exc)
+
+
+@router.post("/{network_id}/connect")
+def connect_container(
+    network_id: str,
+    body: ContainerRef,
+    request: Request,
+    session: Session = Depends(get_session),
+    user: User = Depends(require_admin),
+) -> dict:
+    try:
+        network_service.connect_container(network_id, body.container, body.aliases)
+    except DockerError as exc:
+        _map(exc)
+    audit_service.record(
+        session, user=user.username, action="network.connect", target=network_id,
+        detail=body.container, ip=_ip(request),
+    )
+    return {"ok": True}
+
+
+@router.post("/{network_id}/disconnect")
+def disconnect_container(
+    network_id: str,
+    body: ContainerRef,
+    request: Request,
+    session: Session = Depends(get_session),
+    user: User = Depends(require_admin),
+) -> dict:
+    try:
+        network_service.disconnect_container(network_id, body.container, body.force)
+    except DockerError as exc:
+        _map(exc)
+    audit_service.record(
+        session, user=user.username, action="network.disconnect", target=network_id,
+        detail=body.container, ip=_ip(request),
+    )
+    return {"ok": True}
 
 
 @router.post("", status_code=201)