Regularity witness

A compact payload whose format depends on rs_regularity_method. An empty string means the method needs no payload; NULL means nothing is stored.

• direct_mixed_jacobian: empty when regular, otherwise the comma-separated non-regular primes.
• direct_vertical_fiber_jacobian: empty when regular, otherwise its non-regular prime.
• three_lines_deletion: e=>target_id, the deleted element and the target's id.
• simple_core: the id of the simple core.
• smooth: normally empty. 809 rows keep an older, still valid e=>target_id deletion witness.
• unresolved_*: restart metadata primes=p1,p2,...;basis=b1,b2,b3;attempts=N. This is not a certificate either way.
• all other methods: empty.

Full details: docs/realization_scheme_singularity_census.md (Section 18.1).