## 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`