feat: Normalize remote plugin summary identities. (#22265)

Makes plugin summaries use config-style plugin@marketplace IDs while
exposing backend remote IDs separately as remotePluginId.

Also fix the consistency issue of REMOTE_SHARED_WITH_ME_MARKETPLACE_NAME

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

@@ -538,6 +538,8 @@ pub enum PluginAvailability {
 #[ts(export_to = "v2/")]
 pub struct PluginSummary {
     pub id: String,
+    /// Backend remote plugin identifier when available.
+    pub remote_plugin_id: Option<String>,
     pub name: String,
     /// Remote sharing context associated with this plugin when available.
     pub share_context: Option<PluginShareContext>,