Add GigaAM backend and ASR benchmark

release 1.0

add PETG in preheat menu

pre bltouch tests

name

motion: calibrate input shaping to 36.4Hz damping 0.10

ZV input shaping: 36.5

motion: enable ZV input shaping for XY

motion: set XY acceleration limits and calibrated defaults

baseline: Marlin 2.1.2.8 configured firmware

Document production activation

Make secret setup instructions idempotent

Refresh README for current deployment

Document and validate external MAX secrets

Separate tracked config from server secrets

Use a single server secrets file

Add server secrets template

Implement Disk Health Monitor v1