The iBeacon branch guarded on `l >= 20` but reads p[20] (the Tx-power byte),
so a payload clamped to exactly 20 bytes read one byte past the advertising
data. Require the full 21 bytes (16 UUID + 2 major + 2 minor + 1 Tx).
Extract the reusable BLE central/GATT client and name/value decoders into
libble/ (moved out of bt_inspector). build.sh now stages libble/*.{c,h}
into each app dir at build time and builds every app in APPS=(...).
New app ble_hid_host: connects to a BLE keyboard or mouse, discovers the
HID service (0x1812), sets protocol mode (boot when offered, else report),
subscribes to the input-report characteristics, and decodes keyboard
(modifiers + key names) and mouse (buttons + dx/dy/wheel) reports live.
Events scroll on screen and are logged with raw bytes to
apps_data/ble_hid_host/. No pairing, so encryption-gated keyboards stay
silent; open devices and most mice work. Both faps build and pass APPCHK.
andy