12-OBD-Speed: settings page with screen rotation (0/90/180/270)

- third tile (swipe left from the menu): rotation buttons, saved in NVS,
  applied at boot
- shared lib: setRotation() rotates only the panel and redraws; touch
  points are converted in touchpad_read() for the current rotation;
  getRotation() added

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

12-OBD-Speed/README.md

@@ -9,6 +9,7 @@ Uses the shared board library and LVGL 9.6 (`../shared`), NimBLE-Arduino 2.5.1.
 - **Swipe left → adapter menu** — scans while open. OBD-like adapters (name OBD/ELM/…, or service FFF0/FFE0/18F0)
   are listed first in green. **Tap one** to select it: it is remembered (NVS) and connected immediately.
   **Forget** clears the remembered adapter, **Done** (or swipe right) returns to the speed page.
+- **Swipe left again → settings** — screen rotation 0 / 90 / 180 / 270 degrees (tap to apply; remembered in NVS, applied at boot).
 - On power-up the remembered adapter is connected automatically; if the link drops or the adapter is not
   there (car off), it retries every 3 s. With no adapter remembered, the device starts on the menu page.