Finalize remaining cases coherently when force-ending a meeting

Meetings 10–15 were force-ended after the sequential-case-start defect left cases unstarted. Meeting 15 changed to “Møtet er over” but five unstarted cases and a reopened case remained individually actionable with “Avslutt sak”; they had to be ended one by one after the meeting was already over. Other meetings left unstarted cases indefinitely on public/politician pages while protocol showed only completed cases. Define and enforce force-end semantics atomically: close/archive remaining cases consistently, prevent post-end case lifecycle actions, and align protocol/public/politician categorization. Preserve audit history and do not fabricate decisions for untreated proposals. Add mixed ongoing/not-started/ended case coverage.