X72-52: Coupled Floquet Rescue and Source-Debt Export

Building on Round 51's central viscous-curvature obstruction, this round directly tests whether it lies within the source range of the hidden kernel. The result proves that a compact hidden block occupying just two vertical sidebands already gives a nonzero central-source projection that exactly cancels that central curvature, so Round 51's 'central obstruction' is reclassified: a rescue does exist; but that same rescue block necessarily exports source debt to adjacent and higher sidebands (same-layer export at order O(ν), cross-parity viscous export at order O(ν²)), so the rescue is not in fact closed. Route halts at STOP-C56 (source-debt cascade / Floquet-tail convergence gap), handed to the next round to study the asymptotic behavior of source transfer for general hidden blocks at large sideband depth; this round also includes a numerical-verification script.