* fix(server): validate workspace membership for subscription targets and file uploads
Closes MED-1 (cross-workspace subscription injection) and MED-2 (file upload
missing workspace member validation) from the security audit.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
* test(server): add negative tests for cross-workspace subscription and upload
Address PR review feedback:
- Add tests verifying cross-workspace user_id is rejected with 403 on
subscribe and unsubscribe
- Add test verifying upload with foreign workspace_id is rejected with 403
- Make isWorkspaceEntity explicitly enumerate "member"/"agent" and reject
unknown user types
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
---------
Co-authored-by: Devv <devv@Devvs-Mac-mini.local>
Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
