M.4 Contact collapse and Helmholtz conditions

.4 status. Constructed in the formal, $\chi$-plateau, preparation-plateau, double-plateau and time-only readings (Gate S-bv certified): the collapse ranks, the SA subspaces, the variational images, the Helmholtz certificates, and the matching probes. Under Gate V: the formal collapse image has no variational $D\ge 1$ tensors; the preparation-plateau variational image is likewise only the $26$-dimensional ultralocal family; the specified quadratic Einstein–Hilbert Euler tensor is not in the selected double-plateau collapse image. Fixed-data: criteria, universal region comparisons and the time-only classification in Stage 2 (Propositions prop:fixed-crit, prop:fixed-regions, Theorem thm:to-timeonly); actual fixed-data dimensions unresolved where ${\chi }_{\mathrm{I}}$ is non-constant; not assumed settled by formal $D\ge 1$ vanishing. Unresolved: physical normalization ($\kappa$, $\hslash$, $i$); actual fixed-data dimensions where ${\chi }_{\mathrm{I}}$ is non-constant; whether transition-region contributions near plateau edges can be absorbed by insertion or switch counterterms.