fix: add github network ecosystem for MCP server API access

The github MCP server container needs to reach api.github.com
to fulfill issue reads. network: defaults only covers basic
infrastructure, not GitHub domains.

Add github, containers, and nsip.org to network allowed list.

Author: zircote

.github/workflows/flock-action.lock.yml

@@ -11,7 +11,12 @@ on:
 
 permissions: read-all
 
-network: defaults
+network:
+  allowed:
+    - defaults
+    - github
+    - containers
+    - "nsip.org"
 
 tools:
   edit: