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.

pyproject.toml

@@ -0,0 +1,23 @@
+[build-system]
+requires = ["scikit-build-core>=0.10", "nanobind>=2.4"]
+build-backend = "scikit_build_core.build"
+
+[project]
+name = "track-core"
+version = "0.1.0"
+description = "Platform-neutral TrackBackFwd track simulation core with Python bindings"
+readme = "README.md"
+requires-python = ">=3.9"
+dependencies = []
+
+[project.optional-dependencies]
+emulator = ["dearpygui>=1.10,<2"]
+test = ["pytest>=8.0"]
+
+[tool.scikit-build]
+minimum-version = "build-system.requires"
+wheel.packages = ["python/track_core"]
+
+[tool.scikit-build.cmake.define]
+TRACK_CORE_BUILD_PYTHON = "ON"
+TRACK_CORE_BUILD_TESTS = "OFF"