X72-25: Nonlocal Cross-Blob Virtual Connectivity

Continuing from Round 24's result that 'local viscous neck communication can be made arbitrarily slow by separation distance,' this round reintroduces the nonlocal pressure Hessian and whole-space Biot–Savart strain/velocity coupling, measuring the decay rate of the cross-region field: cross-velocity ~R⁻², cross-strain and cross-pressure-Hessian ~R⁻³, whereas neck heat diffusion decays in a Gaussian/exponential fashion — so at fixed time and large separation the algebraic coupling can dominate the Gaussian neck communication. But it proves that the cross-term sign has no universal direction (the cross sign of both strain and pressure is indefinite), and that virtual connectivity does not imply positive conductance, thereby clearly distinguishing two independent concepts — 'mass conductance h_Q' and 'nonlocal dynamical connection' (duplex connectivity). The route halts at STOP-C29 (virtual-connectivity / sign-coherence gap), passing the baton to the next round to ask whether strain geometry or critical-mass tilt can force this signed kernel toward synchronization on the dangerous branch.