nx_f64_oracle_sov.nx

nx_f64_oracle_sov.nx -- SOVEREIGN f64 oracle: pure-Nishi independent recompute of IEEE 754 binary64 add/sub/mul/div/sqrt expected values (operator law: no py, no sh -- the Python vector generator becomes a retired debt for ME0). INDEPENDENCE: this is a structurally different path from nx_f64. The impl rounds through per-op guard/sticky shortcuts (sticky-jam GRS); the oracle carries the EXACT result in a two-word 120-bit significand (hi:lo, 60 bits per word) plus a sticky flag, finds the true msb, and rounds from the full value. Anchor proof: _f64_soak_gate_authored phase 1 reproduces ALL 1217 hardware-IEEE-anchored KAT expected values; phase 2 soaks random vectors impl-vs-oracle (sovereign xorshift PRNG). Word convention: value = (hi*2^60 + lo) * 2^(e112 - 1135); a normal 53-bit significand sig placed at hi=sig, lo=0 has its msb at bit 112 and biased exponent e112. orc_pack derives eo = e112 + (msb - 112), denormalizes below eo=1 into sticky, rounds to nearest even from the exact tail. license_tier: ORIGINAL