`GET /api/info` now carries `build` (commit hash, commit date, dirty flag)
and `instance`, a fresh uuid per daemon process. Together they let a client
name the release it is talking to and, after losing its socket, tell an
upgrade from a plain restart from a network blip.
The stamp comes from `maestro-daemon/build.rs`, which reads the git checkout
it compiles in. The Nix build has no `.git` in the crane-filtered source, so
`flake.nix` passes the flake's own revision and last-modified date through
`MAESTRO_BUILD_*` instead. Neither available leaves the fields empty.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
