Let edge nodes read /systems with their own api_key

The node builds its OP25 config from GET /systems, but that router only
accepted a Firebase token or the shared service key — a node holds neither.
Every fetch returned 401 and the node fell back to its stale offline cache,
so a system edited in the UI never reached the field. Confirmed on node-002
against the live server: "Failed to fetch systems from C2: 401 Unauthorized
... Offline cache will be used."

The node sends no node_id with the request, only the bearer token, so the
key is matched by querying node_keys for the value instead of fetching a
known document the way /upload does.

Read access only: the mutating routes in this router each carry their own
require_admin_token, so widening the router-level gate doesn't let a node
create, edit or delete a system.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

drb-c2-core/app/internal/auth.py

@@ -37,6 +37,41 @@ async def require_service_or_firebase_token(
         raise HTTPException(status_code=401, detail="Invalid or expired token")
 
 
+async def require_node_service_or_firebase_token(
+    credentials: Optional[HTTPAuthorizationCredentials] = Security(_bearer),
+) -> dict:
+    """Accept a node's own API key in addition to a service key / Firebase token.
+
+    Edge nodes need to read ``/systems`` to build their OP25 config, but they
+    hold neither a Firebase token nor the shared service key — only the
+    per-node api_key that ``/upload`` already trusts. Without this they got a
+    flat 401 and silently fell back to their stale offline cache, so a system
+    edited in the UI never reached the node.
+
+    Unlike ``/upload``, the node sends no node_id alongside the bearer token,
+    so the key is matched by querying ``node_keys`` for the value rather than
+    fetching a known document. Mutating routes are unaffected: they carry
+    their own ``require_admin_token`` dependency, so widening the router-level
+    gate grants nodes read access only.
+    """
+    if not credentials:
+        raise HTTPException(status_code=401, detail="Missing authorization token")
+    token = credentials.credentials
+    if settings.service_key and secrets.compare_digest(token, settings.service_key):
+        return {"service": True}
+    try:
+        return firebase_auth.verify_id_token(token)
+    except Exception:
+        pass
+    # Deferred import: app.internal.firestore initialises firebase-admin at
+    # import time, and auth.py is imported from module scope in the routers.
+    from app.internal import firestore as fstore
+    matches = await fstore.collection_list("node_keys", api_key=token)
+    if matches:
+        return {"node": True, "node_id": matches[0].get("node_id")}
+    raise HTTPException(status_code=401, detail="Invalid or expired token")
+
+
 def get_role(decoded: dict) -> str:
     """Extract the effective role from a decoded Firebase token.