Opus 5 #50 innovation: 534-dim positive-definiteness certified in under 1 second

The #50 disproof introduced a new reusable trick: instead of exact LDL on a 534×534 rational matrix, round the float Cholesky inverse to an integer U and check the single exact inequality ‖UᵀMU − s²I‖_F² < s⁴. Result: 534-dimensional positive-definiteness certified in under 1 second, numpy-only. This bypasses the computational bottleneck that makes large exact-LDL infeasible. The technique is generalizable to future high-dimensional PD-certificate needs.