refactor(track-core): remove app-facing track adapters

Keep track-core focused on portable track state, scheme runtime, PID runtime, memory strip, and render planning.

Remove the ESP-IDF/nanopb Track adapter headers and sources from the submodule so app/protobuf ownership can live in a separate firmware component.

The standalone CMake and Python binding surface remains unchanged, including the emulator-facing APIs.

README.md

@@ -5,6 +5,10 @@ Standalone C++ core for TrackBackFwd track simulation and strip rendering.
 This library is intentionally platform-neutral. It does not depend on ESP-IDF,
 FreeRTOS, protobuf/nanopb, BLE, or hardware LED drivers.
 
+Firmware protobuf/ESP-IDF adapter types for the Track service live in
+`components/app_track_model` in the parent project. Keep this package focused on
+portable track state, scheme decoding/runtime, PID runtime, and render planning.
+
 ## Build
 
 ```bash
@@ -14,7 +18,7 @@ ctest --test-dir build --output-on-failure
 ```
 
 When used inside an ESP-IDF project under `components/track-core`, the same
-`CMakeLists.txt` registers an IDF component.
+`CMakeLists.txt` registers an IDF component for the portable core only.
 
 ## Python bindings