feat(sprint8): Phase 3 — Mitgliederversammlung (assemblies, voting, protocol PDF)

Backend:
- V19 migration: assemblies, assembly_agenda_items, assembly_attendees, assembly_votes, assembly_vote_records
- Enums: AssemblyType, AssemblyStatus, AgendaItemType, VoteType, VoteDecision, VoteResult
- Entities: Assembly, AssemblyAgendaItem, AssemblyAttendee, AssemblyVote, AssemblyVoteRecord
- Repositories: Assembly, AgendaItem, Attendee, Vote, VoteRecord
- AssemblyService: full lifecycle (create, invite, start, attend, vote, quorum, complete)
- AssemblyProtocolService: OpenPDF protocol generation (§147 AO compliant)
- AssemblyController: admin + portal endpoints
- Extended: AuditEventType, NotificationType, StaffPermission

Frontend:
- Assembly service with full API client and TypeScript types
- Admin assemblies list page with create dialog (agenda builder)
- Admin assembly detail page (quorum, agenda, votes, attendees)
- Navigation: Versammlungen with Gavel icon (after Finanzen)

Legal basis: §32-§40 BGB (Mitgliederversammlung), §147 AO (retention)

cannamanage-frontend/src/app/(marketing)/layout.tsx

@@ -18,7 +18,7 @@ export default async function MarketingLayout({
 
   return (
     <NextIntlClientProvider messages={messages}>
-      <div className="min-h-screen flex flex-col bg-background text-foreground">
+      <div className="min-h-screen flex flex-col bg-background text-foreground overflow-x-hidden">
         {/* Header */}
         <header className="sticky top-0 z-40 border-b bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
           <div className="container mx-auto flex h-16 items-center justify-between px-4">