nx_h264_fdct.nx

nx_h264_fdct.nx -- H.264 FORWARD 4x4 integer transform + forward quantization (the ENCODE counterpart of the existing decode-side nx_h264_idct + nx_h264_dequant). This is the core rung of the sovereign H.264 ENCODER (R6, for HEVC->H.264 transcode): residual -> coefficients -> quantized levels, validated by round-tripping back through the proven inverse pieces. The core transform Cf (rows then cols): [1 1 1 1; 2 1 -1 -2; 1 -1 -1 1; 1 -2 2 -1], in butterfly form (no floats). Forward quant uses the standard MF[qp%6][posClass] multiplier matrix + dead-zone f, matching the inverse normAdjust/V table so the pair round-trips. Reuses nx_dq_posclass for the position class (DRY, identical to the dequant). ITU-T H.264 transform is public -> patent-clean for the integer math. license_tier: ORIGINAL