Matches the SMEM layout: float_e2m1_unpacksmem_t is 1 byte/element. L1→L2 handoff uses unpacked format (same byte count as FP8). No bandwidth savings at L1→L2 for v1 — can optimize later.
mxf4nvf4 requires FP4×FP4, not FP8×FP4. - New staging kernel: E2M1 nearest-neighbor quantization - Output: uint8 packed (2 E2M1 per byte) + UE4M3 packed int32 scales - Added CUDA sync diagnostics for error localization