[codex] expose remote plugin share URL (#27890)

## Summary

- expose the remote plugin detail endpoint's `share_url` as nullable
`PluginDetail.shareUrl`
- preserve existing `PluginSummary.shareContext` behavior for local and
workspace sharing flows
- regenerate the app-server TypeScript and JSON schema fixtures

## Why

The remote plugin detail response already includes a canonical
`share_url`, but that value was not surfaced by `plugin/read` for global
plugins. Global plugins intentionally have no `shareContext`, so using
that model for the URL would change the semantics consumed by the
existing share modal.

## User impact

Codex clients can use `PluginDetail.shareUrl` for a remote plugin's
copy-link action, including when the plugin is disabled by an
administrator, without changing existing share-modal or ownership
behavior.

## Validation

- `cargo test -p codex-app-server
plugin_read_includes_share_url_for_admin_disabled_remote_plugin`
- `cargo test -p codex-app-server-protocol
typescript_schema_fixtures_match_generated`
- `cargo test -p codex-app-server-protocol
json_schema_fixtures_match_generated`
- `cargo fmt --all`

codex-rs/tui/src/chatwidget/tests/helpers.rs

@@ -1421,6 +1421,7 @@ pub(super) fn plugins_test_detail(
         marketplace_name: "ChatGPT Marketplace".to_string(),
         marketplace_path: Some(plugins_test_absolute_path("marketplaces/chatgpt")),
         summary,
+        share_url: None,
         description: description.map(str::to_string),
         skills: skills
             .iter()

codex-rs/tui/src/chatwidget/tests/popups_and_settings.rs

@@ -803,6 +803,7 @@ async fn plugin_detail_remote_install_uses_remote_location() {
                 marketplace_name: "workspace-shared-with-me-private".to_string(),
                 marketplace_path: None,
                 summary,
+                share_url: None,
                 description: Some("Install shared Linear plugin.".to_string()),
                 skills: Vec::new(),
                 hooks: Vec::new(),
@@ -877,6 +878,7 @@ async fn plugin_detail_remote_uninstall_uses_remote_plugin_id() {
                 marketplace_name: "workspace-shared-with-me-private".to_string(),
                 marketplace_path: None,
                 summary,
+                share_url: None,
                 description: Some("Installed shared Linear plugin.".to_string()),
                 skills: Vec::new(),
                 hooks: Vec::new(),
@@ -949,6 +951,7 @@ async fn plugin_detail_remote_without_remote_id_disables_uninstall_action() {
                 marketplace_name: "workspace-shared-with-me-private".to_string(),
                 marketplace_path: None,
                 summary,
+                share_url: None,
                 description: Some("Installed shared Linear plugin.".to_string()),
                 skills: Vec::new(),
                 hooks: Vec::new(),