Otis-Lab-MUSC/reacher-firmware: v2.1.0 — Final archived release

Terminal release of the standalone `reacher-firmware` repository. Active firmware development has moved into `Otis-Lab-MUSC/reacher` under `firmware/`; compiled hex now ships inside the `reacher` PyPI package. This repository is read-only — open firmware issues and PRs against `Otis-Lab-MUSC/reacher`. Highlights since v2.0.0 Per-device lever routing filters (378/388/478/488) and onset-delay commands (377/387/477/487) for fr, pr, vi, omission. Action-level lever source filtering with shadow-global persistence across chain rebuilds. Board target migrated to Arduino Mega 2560 (ATmega2560); compile.sh builds hex/mega/. Firmware version strings reconciled to 2.1.0 across library.properties, sketch SendIdentification() reports, and docs. 📖 Citing this firmware The version referenced in the published protocol is `v1.0.1-alpha` ("Version for Protocol paper"), preserved unchanged for reproducibility. Cite that release, not `v2.1.0`, when reproducing the paper. See CHANGELOG.md for full details.