CodSpeed's CMake uses CODSPEED_ANALYSIS (not CODSPEED_SIMULATION) for
simulation mode. This define gates all the actual benchmark measurement
hooks in benchmark_runner.cpp and benchmark.h. Without it, benchmarks
run normally but CodSpeed doesn't detect them as instrumented.
- Move BASE_CODEGEN_COMPONENTS and USE_TIME_TIMEZONE_FLAG to test_helpers.py
- Use shared constants in both cpp_unit_test.py and cpp_benchmark.py
- Move json import to top level in cpp_benchmark.py
- Refactor setup_codspeed_lib.py into focused helper functions
- Combine clone + submodule init, use --shallow-submodules
- Use CodSpeed's codspeed-cpp fork with proper instrumentation for
simulation mode benchmark detection
- setup_codspeed_lib.py creates a flat PlatformIO-compatible library
by combining google_benchmark sources, codspeed core, and
instrument-hooks into a single library directory
- Renames .cc to .cpp (PlatformIO doesn't compile .cc by default)
- Adds all required defines: CODSPEED_ENABLED, CODSPEED_SIMULATION,
CODSPEED_VERSION, CODSPEED_ROOT_DIR, CODSPEED_MODE_DISPLAY
- Output JSON config consumed by cpp_benchmark.py via env var