Add multi-agent runtime metadata types (#25720)

Stack split from #25708. Original PR intentionally left open. This first
PR adds the multi-agent runtime metadata types and catalog plumbing used
by the rest of the stack.

codex-rs/models-manager/src/model_info.rs

@@ -101,6 +101,7 @@ pub fn model_info_from_slug(slug: &str) -> ModelInfo {
         supports_search_tool: false,
         auto_review_model_override: None,
         tool_mode: None,
+        multi_agent_version: None,
     }
 }