nx_recip_div_w.nx

nx_recip_div_w.nx -- the Newton/Goldschmidt reciprocal divider as a WIDTH- PARAMETERIZED gate-network generator (W in [17,30]) -- the Seed-style "emit the optimal form for the target", generalised from the W=24 instance. Composes the proven 64x64->128 wide multiplier for the only product that overflows i64 (x*t). Envelope: W in [17,30]. The upper bound is where 2F^2 = 2^(2W+1) still fits i64 (W=30 -> 2^61 < 2^63; W=31 -> 2^63 = INT_MIN, breaks). Below it every product but x*t fits a single MUL; x*t (<= 2^(3W+2)) is built 128-bit and shifted >>2W via x = (hi << (64-2W)) | ((lo >> 2W) & ((1<<(64-2W)) - 1)). Seed = the minimax (48F-32Dn)/17 (~4 bits, scale-invariant), 3 Newton iters (-> ~32 bits >= W), KCORR=3 (maxcorr<=1 over the envelope). license_tier: ORIGINAL