Add BT Inspector: BLE scanner and GATT explorer for Flipper Zero

Built-in firmware app (needs the full ST BLE stack) with live RSSI-sorted
scan list, advertisement decoding (Apple Continuity, Microsoft CDP, Fast
Pair, Eddystone), connect/discover/read/write/notify, device-info summary,
value history and a timestamped session log. build.sh produces a firmware
update package with COPRO_STACK_TYPE=ble_full and the app compiled in.

.gitignore

@@ -0,0 +1,6 @@
+flipperzero-firmware/
+.venv/
+build.log
+*.log
+__pycache__/
+dist/