feat(track-core): add portable training runtimes

Move scheme and PID training runtime behavior into the pure track_core layer and expose render sinks for injected strip application.

Add ESP compatibility adapters, Python bindings/test scaffolding, and in-memory render support so app_track_bt can consume core render and runtime logic without duplicating it.

Cover circular/linear rendering boundaries, all scheme runtime types, scheme render_to parity, PID sample de-duplication, speed suppression, and live tuning in track-core tests.

CMakeLists.txt

@@ -2,14 +2,27 @@ set(TRACK_CORE_SOURCES
     src/memory_strip.cpp
     src/model.cpp
     src/pid_program.cpp
+    src/pid_runtime.cpp
     src/render.cpp
     src/scheme_decoder.cpp
+    src/scheme_runtime.cpp
 )
 
 if(DEFINED IDF_TARGET)
+    set(TRACK_CORE_IDF_SOURCES
+        src/esp/app_track_decoder.cpp
+        src/esp/app_track_drawer.cpp
+        src/esp/app_track_model.cpp
+    )
+
     idf_component_register(
-        SRCS ${TRACK_CORE_SOURCES}
+        SRCS ${TRACK_CORE_SOURCES} ${TRACK_CORE_IDF_SOURCES}
         INCLUDE_DIRS include
+        REQUIRES
+            app_proto
+            app_strip_if
+            app_utils
+            app_utils_clock
     )
 else()
     cmake_minimum_required(VERSION 3.20)
@@ -25,7 +38,21 @@ else()
     )
     target_compile_features(track_core PUBLIC cxx_std_23)
 
+    option(TRACK_CORE_BUILD_PYTHON "Build Python bindings" OFF)
     option(TRACK_CORE_BUILD_TESTS "Build track-core tests" ON)
+
+    if(TRACK_CORE_BUILD_PYTHON)
+        find_package(Python 3.9 COMPONENTS Interpreter Development.Module REQUIRED)
+        find_package(nanobind CONFIG REQUIRED)
+
+        nanobind_add_module(_core
+            src/python/bindings.cpp
+        )
+        target_link_libraries(_core PRIVATE track_core::track_core)
+        target_compile_features(_core PRIVATE cxx_std_23)
+        install(TARGETS _core LIBRARY DESTINATION track_core)
+    endif()
+
     if(TRACK_CORE_BUILD_TESTS)
         enable_testing()
         add_executable(track_core_tests tests/track_core_tests.cpp)