f71923b67d
- Add cfar_ca.v: CA/GO/SO-CFAR with BRAM magnitude buffer, host-configurable guard cells, training cells, alpha multiplier, and mode selection - Replace old threshold detector block in radar_system_top.v with cfar_ca instantiation; backward-compatible (cfar_enable defaults to 0) - Add 5 new host registers: guard (0x21), train (0x22), alpha (0x23), mode (0x24), enable (0x25) - Expose doppler_frame_done_out from radar_receiver_final for CFAR frame sync - Add tb_cfar_ca.v standalone testbench (14 tests, 24 checks) - Add Group 14 E2E tests: 13 checks covering range-mode (0x20) and all CFAR config registers (0x21-0x25) through full USB command path - Update run_regression.sh with CFAR in lint, Phase 1, and integration compiles