Document the ADAU1701 schematic chain (sigma-chain.jpg), cross-link from
hardware/firmware chapters, skip safeload on fixed high-pass band 0, and
match EqProfile default peaking frequencies to SigmaStudio.
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>