Expose multi-agent versions in model/list (#37433)

## What changed

- Add nullable `multiAgentVersion` metadata to v2 `model/list` responses.
- Represent supported values as `disabled`, `v1`, or `v2` in the Rust API and generated JSON Schema and TypeScript exports.
- Forward the value from model catalog presets through app-server responses.

## Testing

- Extend the remote model catalog test fixture with a `v2` multi-agent version.

GitOrigin-RevId: bd3b2bbe0a3b562b4d1f03df7da2a73a35713978

codex-rs/app-server-protocol/src/protocol/v2/model.rs

@@ -7,6 +7,7 @@ use codex_protocol::openai_models::ReasoningEffort;
 use codex_protocol::openai_models::default_input_modalities;
 use codex_protocol::protocol::ModelRerouteReason as CoreModelRerouteReason;
 use codex_protocol::protocol::ModelVerification as CoreModelVerification;
+use codex_protocol::protocol::MultiAgentVersion as CoreMultiAgentVersion;
 use serde::Deserialize;
 use serde::Serialize;
 use serde_json::Value as JsonValue;
@@ -23,6 +24,15 @@ v2_enum_from_core!(
     }
 );
 
+v2_enum_from_core!(
+    /// Multi-agent runtime supported by a model.
+    pub enum MultiAgentVersion from CoreMultiAgentVersion {
+        Disabled,
+        V1,
+        V2
+    }
+);
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, Default, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
@@ -96,6 +106,8 @@ pub struct Model {
     pub input_modalities: Vec<InputModality>,
     #[serde(default)]
     pub supports_personality: bool,
+    /// Multi-agent runtime declared by this model, when available.
+    pub multi_agent_version: Option<MultiAgentVersion>,
     /// Deprecated: use `serviceTiers` instead.
     #[serde(default)]
     pub additional_speed_tiers: Vec<String>,