fix: align marketplace display name with existing interface conventions (#14886)

1. camelCase for displayName;
2. move displayName under interface.

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

@@ -3276,10 +3276,17 @@ pub struct SkillsListEntry {
 pub struct PluginMarketplaceEntry {
     pub name: String,
     pub path: AbsolutePathBuf,
-    pub display_name: Option<String>,
+    pub interface: Option<MarketplaceInterface>,
     pub plugins: Vec<PluginSummary>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct MarketplaceInterface {
+    pub display_name: Option<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, Copy, PartialEq, Eq, JsonSchema, TS)]
 #[ts(export_to = "v2/")]
 pub enum PluginInstallPolicy {