Use enum default for realtime v2

Make RealtimeConversationVersion::V2 the derived default and remove the custom RealtimeConfig default implementation.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/config/src/config_toml.rs

@@ -457,7 +457,7 @@ pub enum RealtimeTransport {
 pub use codex_protocol::protocol::RealtimeConversationVersion as RealtimeWsVersion;
 pub use codex_protocol::protocol::RealtimeVoice;
 
-#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Eq, JsonSchema)]
+#[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
 #[schemars(deny_unknown_fields)]
 pub struct RealtimeConfig {
     pub version: RealtimeWsVersion,
@@ -467,17 +467,6 @@ pub struct RealtimeConfig {
     pub voice: Option<RealtimeVoice>,
 }
 
-impl Default for RealtimeConfig {
-    fn default() -> Self {
-        Self {
-            version: RealtimeWsVersion::V2,
-            session_type: RealtimeWsMode::default(),
-            transport: RealtimeTransport::default(),
-            voice: None,
-        }
-    }
-}
-
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
 #[schemars(deny_unknown_fields)]
 pub struct RealtimeToml {

codex-rs/protocol/src/protocol.rs

@@ -1649,8 +1649,8 @@ pub struct HookCompletedEvent {
 #[derive(Debug, Clone, Copy, Default, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
 #[serde(rename_all = "snake_case")]
 pub enum RealtimeConversationVersion {
-    #[default]
     V1,
+    #[default]
     V2,
 }