## Why
Remote plugin sync results need to identify which runtime categories may require
invalidation when a cached bundle changes.
## What changed
- Add `RemotePluginCapabilities` hints for MCP servers, Apps, hooks, and skills.
- Attach capability hints to materialized and removed plugins. Updates union the
declarations from the old and new bundles, while removals inspect the active
bundle before deleting its cache.
- Discover declarations without applying runtime policy or creating runtime
data directories.
## Testing
- Cover Agent Plugin capability discovery with an unavailable runtime data
directory.
- Cover capability accumulation across bundle versions and removal reporting.
GitOrigin-RevId: 338075d22d86f30f52be5785a2d87c77b33609c6