fix(citizens): Fix PublicCitizenSummary slug validation error

- Made slug optional in PublicCitizenSummary model
- Added fallback to agent id if public_slug is None

services/city-service/models_city.py

@@ -358,7 +358,7 @@ class AgentSummary(BaseModel):
 
 
 class PublicCitizenSummary(BaseModel):
-    slug: str
+    slug: Optional[str] = None  # Can be None if public_slug not set
     display_name: str
     public_title: Optional[str] = None
     public_tagline: Optional[str] = None

services/city-service/routes_city.py

@@ -675,7 +675,7 @@ async def list_public_citizens(
                 )
             
             items.append(PublicCitizenSummary(
-                slug=citizen["public_slug"],
+                slug=citizen.get("public_slug") or citizen.get("id"),
                 display_name=citizen["display_name"],
                 public_title=citizen.get("public_title"),
                 public_tagline=citizen.get("public_tagline"),