## Why
Remote exec-server registry requests need to refresh managed credentials before sending a request. Static auth-header resolution cannot perform the asynchronous token exchange required by workload identity.
## What changed
- Add asynchronous auth-header resolution to `AuthProvider`, with the existing static-header behavior as the default.
- Resolve fresh managed credentials for each remote environment registry request while preserving the expected account and workspace identity.
- Load the cloud configuration bundle during remote exec-server startup when workload identity is selected.
## Testing
- Update the managed-auth and environment-registry auth tests to exercise asynchronous header resolution.
GitOrigin-RevId: 5d60f1127467aaacdb5d1a8f3d92278bc4bf2e29