fix: await get_all() in registry router and align get_all key names

The /registry/agents endpoint was 500 on every call because
AgentRegistry.get_all() is async but was called without await.
Also aligns get_all() dict keys (name, domain) with what the router reads.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

agent_service/agents/registry.py

@@ -62,9 +62,10 @@ class AgentRegistry:
     async def get_all(self):
         return [
             {
+                'name': k,
                 'agent_key': k,
+                'domain': self._capabilities.get(k, ''),
                 'active': k in self._active,
-                'capabilities_summary': self._capabilities.get(k, ''),
                 'has_instance': k in self._agents,
             }
             for k in self._agents