The previous gate was typecheck + web build only — no lint, no Python,
no Rust, none of the 24 backend test files. Adds:
- biome lint to the frontend job
- backend-quality on macos-14 (matches the primary user platform so
the MLX-path tests run): just setup-python, ruff check, pytest
- rust-quality: cargo check with stub sidecar binaries, since
tauri-build validates externalBin paths and real sidecars only exist
in the release pipeline
- concurrency group so superseded runs cancel
All gates verified green locally before being wired in.
Jamie Pine