Extends IZaakSource with RecordBesluit, mirroring WP-50's CreateZaak write
pattern: OpenZaakZaakSource POSTs a new Statussen entry (highest-volgnummer
statustype, since the harness catalogus has no per-outcome besluittype),
carrying the besluit + toelichting in statustoelichting; LocalZaakSource
no-ops. The beoordeling endpoint calls it after the local decision commits,
flagging a failure via RecordZgwDivergence the same way submit's
create-zaak/document writes do — closing WP-60's "second write pair" gap.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>