## Why
Bootstrapping the app-server daemon should preserve an explicitly selected release, even when that version is currently `latest`. Older managed binaries should also be able to serve app-server without supporting the updater command.
## What changed
- Record `latest` selections in `auto-update-version` in both standalone installers and clear the marker for explicit releases.
- Start the daemon updater only for a marked stable release whose binary supports `pid-update-loop`. Existing installs without a marker require a new `latest` installation to enable automatic updates.
- Recheck the selected release under the install lock so an in-flight update cannot overwrite a new pin, including installer calls from older updaters. Recheck selection before restarting app-server or replacing the updater.
- Cancel Unix installer process groups and clean up their owned fallback locks when the updater stops.
## Testing
Add coverage for channel markers, explicit pins of the current latest version, older updater guards, updater command support, and Unix installer cancellation with child-process and lock cleanup.
GitOrigin-RevId: 4d275237bd77d896bf64dc1b85a5bca3608142c7
Eric Traut
adee0b04fa