feat: Add vertical remote plugin collection support (#23584)

- Adds an explicit vertical marketplace kind for plugin/list that
fail-open fetches collection=vertical only when full remote plugins are
disabled.

- Renames the global remote marketplace/cache identity to
openai-curated-remote and materializes remote installs with backend
release versions and app manifests.

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

@@ -144,6 +144,9 @@ pub enum PluginListMarketplaceKind {
     #[serde(rename = "local")]
     #[ts(rename = "local")]
     Local,
+    #[serde(rename = "vertical")]
+    #[ts(rename = "vertical")]
+    Vertical,
     #[serde(rename = "workspace-directory")]
     #[ts(rename = "workspace-directory")]
     WorkspaceDirectory,