Remove legacy DigiRadio_Manual.tex/PDF and stub main.tex; point docs/ at the
canonical manual. Update README and CONTRIBUTING paths.
Co-authored-by: Cursor <cursoragent@cursor.com>
Add ch-api.tex for REST endpoints and boot flow, update ch-firmware,
ch-build, and ch-intro. Extend CONTRIBUTING, instructions, and README
with manual sync checks and API reference.
Co-authored-by: Cursor <cursoragent@cursor.com>