Hot fix/documents being soft deleted

[tsubik]

This is already on production, backfilling to develop branch.

Fix documents being soft-deleted instead of reset

RequiredOperatorDocumentFmu#applies_to_forest_type? compared forest_types
(Strings, since ForestType::TYPES is a HashWithIndifferentAccess) against
forest_type.to_sym, so it was always false for forest-type-scoped required
documents. That made condition 5 in OperatorDocument#destroy always fire, so
documents were soft-deleted instead of reset to doc_not_provided.

Shipped 2026-07-30. Affected exactly 2 documents (19045, 19349), both already
restored by hand — verified point-in-time against all 401 destroy events since
the release; the other 399 were legitimate.

Changes

• Fix the comparison, plus the same bug in check:docs_forest_type_mismatch
• Specs for applies_to_forest_type? and for destroying an FMU document
  (the existing #destroy spec used a country document, which has no fmu_id
  and so never reached that condition — the gap that let this through)
• rake fix:erroneous_document_deletion to clean up what the deletion left
  behind: born-deleted history rows, PaperTrail destroy events, the score row
  it created, and document updated_at. Dry run by default (FOR_REAL=true
  to apply, SKIP_STATISTICS=true to leave statistics for a later backfill).