## Why
A temporary exec-server transport loss could emit a thread environment disconnect notification while the session was still recovering.
## What changed
- Add `EnvironmentConnectionState::Recovering` for interrupted transports and pending session recovery.
- Suppress thread lifecycle notifications during recovery, emit a connected notification after successful recovery, and report disconnection when recovery fails.
- Ignore recovery callbacks from retired clients so they cannot overwrite the connection state during refresh.
## Testing
Add coverage for fast and near-deadline recovery, recovery timeout, rejected session resume, and retired-client callbacks. Extend app-server coverage to verify one lifecycle notification per selected thread and usable `environment/info` after recovery.
GitOrigin-RevId: d6dce5cc5264af29b6f993daa209b93102122e40
