## What changed
- Add nullable `canPublishToWorkspace` metadata to plugin share contexts and `plugin/share/save` responses.
- Preserve the remote capability through catalog parsing and app-server responses so clients can decide whether to offer workspace-directory publishing.
- Document that clients should fail closed when the capability is unavailable.
## Testing
- Cover remote catalog parsing, share-save response propagation, and protocol serialization.
GitOrigin-RevId: b0346b3b330169838f800dfdf21dfa5db1a47f4d
1. Adds v2 plugin/share/save, plugin/share/list, and plugin/share/delete
RPCs.
2. Implements save by archiving a local plugin root, enforcing a size
limit, uploading through the workspace upload flow, and supporting
updates via remotePluginId.
3. Lists created workspace plugins
4. Deletes a previously uploaded/shared plugin.
