Add 11-BLE-Scanner: on-screen BLE scanner, inspector and ELM327 test

- NimBLE-Arduino 2.5.1, BLE work in a background task on core 0
- LVGL 9 UI for the round screen: device list (OBD-like devices in green),
  tap to list services/characteristics, ELM test (ATZ/ATE0/ATI/ATRV/0100)
- results saved to LittleFS /ble_log.txt; serial d/c/s commands
- shared lv_conf: Montserrat 16 and 20 enabled

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -79,6 +79,7 @@ Display color format is `RGB565_SWAPPED` (ST77916 byte order, set in `lv_conf.h`
 | `1-Instructions` | Spec PDF (duplicate), AIDA64 remote-sensor layout `aida_remote_1.85.rslcd`, MJPEG conversion tool (Windows .NET, converts video to 360×360 MJPEG 25 fps) |
 | `2-Program Example/Demo_Arduino` | **Vendor only:** `library/` (3 libs), `lv_conf.h` (vendor original), `sd/` (SD listing example; its lv_conf.h has FATFS edits), `docs/` (setup screenshots + compile instructions). The vendor's original LVGL demo sketch no longer exists unmodified. |
 | `shared` | **Shared code for all JC3636W518 projects:** `jc3636w518.ini` (PlatformIO base config), `include/lv_conf.h` (LVGL 9.6), `lib/JC3636W518` (board library). See its `README.md` |
+| `11-BLE-Scanner` | **BLE scanner with on-screen UI** (NimBLE-Arduino 2.5.1): live device list, tap to list services/characteristics, ELM327 test (ATZ/ATE0/ATI/ATRV/0100). Results saved to LittleFS `/ble_log.txt`; serial `d` dump, `c` clear, `s` device list. See its `README.md` |
 | `10-OBD-Display-2024` | **Earlier OBD speed-display project**, split into separate sketches — see its `README.md`: `display_speed_wifi`, `display_gif_sd`, `display_gif_embedded`, `elm327_wifi_bridge` (classic ESP32), `elmulator`, `assets/gifs`, `_archive/lvgl9_broken` |
 | `3-Specification` | Spec sheet (factory firmware features, interface photo) |
 | `4-Chip manual` | ESP32-S3R8 datasheet, PCM5100A datasheet |
@@ -94,7 +95,7 @@ Re-flash it with Flash Download Tool: ESP32-S3, `1.85_demo.bin` @ 0x0.
 
 ## OBD adapter (user's)
 AliExpress "ELM327 Mini V2.1 Bluetooth OBD **Dual Mode** 5.1" — dual mode = Bluetooth Classic SPP **and BLE**, so the ESP32-S3 should be able to connect directly over BLE (no bridge ESP32).
-Cheap dual-mode clones typically expose BLE service `FFF0` (notify `FFF1`, write `FFF2`) — **not yet verified** on this adapter; scan it first. Adapter is powered from the car's OBD port (pin 16, 12 V).
+Cheap dual-mode clones typically expose BLE service `FFF0` (notify `FFF1`, write `FFF2`) — **not yet verified** on this adapter; use `11-BLE-Scanner` in the car (results in its flash log). Adapter is powered from the car's OBD port (pin 16, 12 V).
 
 ## Gotchas / observations
 - **LVGL 8 GIF bug (patched locally, only relevant if LVGL 8 is used again):** LVGL 8.3.11 `gifdec.c` (`gd_open_gif`) filled the canvas *opaque* with the GIF's background color. GIFs with a transparent background (e.g. `loligod.gif`, bg = RGB 28,29,49) showed that dark gray except where "restore to background" frames had cleared to transparent (→ screen black). **Patched** in the vendor copy `2-Program Example/Demo_Arduino/library/lvgl/src/extra/libs/gif/gifdec.c`: initial canvas alpha 0x00 (marked `LOCAL PATCH`). Re-apply if LVGL is ever replaced/upgraded.
@@ -113,3 +114,5 @@ Cheap dual-mode clones typically expose BLE service `FFF0` (notify `FFF1`, write
 - Compiling a 13.9 MB GIF into the firmware will not fit "Huge APP" (3 MB); large media should live on SD (or in a custom partition).
 - `display_gif_sd` / `display_speed_wifi` `setup()` return early if the SD card fails to mount (black screen); `display_gif_embedded` starts its GIF first.
 - Draw buffer is in internal RAM; PSRAM is available for larger buffers / images.
+- **LittleFS** works on the `spiffs` partition of `huge_app.csv` (~900 KB); the first mount after flashing formats it (prints `Corrupted dir pair` / `mount failed (-84)` and some `task_wdt ... task not found` once — harmless).
+- BLE (NimBLE) in the user's home: ~12 devices visible within 10 s.