39f78d4349
Previously the S_IDLE->S_ACCUMULATE transition consumed one data_valid cycle without writing to BRAM, losing the first sample. The testbench worked around this by sending sample[0] twice. Fix: drive mem_we + data capture in S_IDLE on the transition cycle and advance write_range_bin to 1. Testbench workaround removed. Verified: 3/3 Doppler co-sim BIT-PERFECT, integration test 10/10 PASS.