Add a Soundpad app screen: a 2x3 grid of colored pads that each emit one of
F13..F18 over the existing BLE HID keyboard, for mapping to a host soundboard.
Key release is deferred via a one-shot LVGL timer so the UI thread never blocks.
Raise the HID report-map keycode ceiling from 101 (0x65) to 115 (0x73) in
ble.cpp so F13..F24 (0x68..0x73) are within the declared key-array range — they
were silently undeliverable before. Wire SCREEN_SOUNDPAD to the real screen
(was a stub).
NOTE: the HID report descriptor changed, so the host must re-pair to refresh its
cached map before F13..F18 are recognized.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
