- Update all docstrings from 14.5 MHz to 12 MHz XOSC (29 files) - Fix 0x05_servo_cbm divider: INT=14/FRAC=8 (14.5) -> INT=12/FRAC=0 (12) - Verified against RP2350 datasheet, Pico 2 board schematic, and SDK
- GPIO15 active-low button input with internal pull-up - 20ms software debounce via busy-wait confirmation - LED mirrors button state, UART reports edge transitions - New gpio_config_input_pullup() in GPIO driver - 1555B FLASH, 13 source files, zero warnings