Fix custom command creation constraint violation

Exclude 'creator' nested object from model_dump when creating custom commands.
The issue was that Pydantic was including both creator_id and creator fields,
causing Peewee to receive a nested dict that resulted in NULL creator_id values
in the database insert, violating the NOT NULL constraint.

This fix ensures only creator_id is passed to the ORM for foreign key mapping.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/routers_v3/custom_commands.py

@@ -368,7 +368,7 @@ async def create_custom_command_endpoint(
             raise HTTPException(status_code=409, detail=f"Command '{command.name}' already exists")
         
         # Create the command
-        command_data = command.model_dump(exclude={'id'})
+        command_data = command.model_dump(exclude={'id', 'creator'})
         command_id = create_custom_command(command_data)
         
         # Update creator stats