Expose plugin manifest keywords in app server (#21271)

## Summary
- Add plugin manifest keywords to core plugin marketplace/detail models
- Expose keywords on app-server v2 PluginSummary and generated
schema/types
- Populate keywords in plugin/list and plugin/read responses for local
plugins

Depends on https://github.com/openai/openai/pull/891087

## Validation
- just fmt
- just write-app-server-schema
- cargo test -p codex-app-server-protocol
- cargo test -p codex-core-plugins
- cargo test -p codex-app-server
plugin_list_keeps_valid_marketplaces_when_another_marketplace_fails_to_load
- cargo test -p codex-app-server
plugin_read_returns_plugin_details_with_bundle_contents

codex-rs/core-plugins/src/remote/share/tests.rs

@@ -442,6 +442,7 @@ async fn list_remote_plugin_shares_fetches_created_workspace_plugins() {
                     auth_policy: PluginAuthPolicy::OnUse,
                     availability: PluginAvailability::Available,
                     interface: Some(expected_plugin_interface()),
+                    keywords: Vec::new(),
                 },
                 share_url: Some("https://chatgpt.example/plugins/share/share-key-1".to_string()),
                 local_plugin_path: Some(local_plugin_path),
@@ -456,6 +457,7 @@ async fn list_remote_plugin_shares_fetches_created_workspace_plugins() {
                     auth_policy: PluginAuthPolicy::OnUse,
                     availability: PluginAvailability::Available,
                     interface: Some(expected_plugin_interface()),
+                    keywords: Vec::new(),
                 },
                 share_url: None,
                 local_plugin_path: None,