feat: Expose plugin versions and gate plugin sharing (#22397)

- Adds localVersion to plugin summaries and remoteVersion to share
context, including generated API schemas.
- Hydrates local and remote plugin versions from manifests and remote
release metadata.
- Adds default-on plugin_sharing gate for shared-with-me listing and
plugin/share/save, with disabled-path errors
    and focused coverage.

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

@@ -540,6 +540,9 @@ pub struct PluginSummary {
     pub id: String,
     /// Backend remote plugin identifier when available.
     pub remote_plugin_id: Option<String>,
+    /// Version of the locally materialized plugin package when available.
+    #[serde(default)]
+    pub local_version: Option<String>,
     pub name: String,
     /// Remote sharing context associated with this plugin when available.
     pub share_context: Option<PluginShareContext>,
@@ -561,6 +564,9 @@ pub struct PluginSummary {
 #[ts(export_to = "v2/")]
 pub struct PluginShareContext {
     pub remote_plugin_id: String,
+    /// Version of the remote shared plugin release when available.
+    #[serde(default)]
+    pub remote_version: Option<String>,
     pub discoverability: Option<PluginShareDiscoverability>,
     pub share_url: Option<String>,
     pub creator_account_user_id: Option<String>,

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

@@ -3007,6 +3007,7 @@ fn plugin_share_list_response_serializes_share_items() {
                     remote_plugin_id: Some(
                         "plugins~Plugin_00000000000000000000000000000000".to_string(),
                     ),
+                    local_version: None,
                     name: "gmail".to_string(),
                     share_context: None,
                     source: PluginSource::Remote,
@@ -3027,6 +3028,7 @@ fn plugin_share_list_response_serializes_share_items() {
                 "plugin": {
                     "id": "gmail@chatgpt-global",
                     "remotePluginId": "plugins~Plugin_00000000000000000000000000000000",
+                    "localVersion": null,
                     "name": "gmail",
                     "shareContext": null,
                     "source": { "type": "remote" },
@@ -3059,6 +3061,7 @@ fn plugin_summary_defaults_missing_availability_to_available() {
     .unwrap();
 
     assert_eq!(summary.availability, PluginAvailability::Available);
+    assert_eq!(summary.local_version, None);
     assert_eq!(summary.share_context, None);
 }