feat(sprint8): Phase 4 — Dokumentenarchiv + Vorstandsverwaltung

Backend:
- V20 migration: documents table with category, access_level, file storage
- V21 migration: board_positions + board_members with term tracking
- Document entity + DocumentCategory/DocumentAccessLevel enums
- BoardPosition + BoardMember entities
- Extended AuditEventType (DOCUMENT_UPLOADED/DELETED, BOARD_MEMBER_ELECTED/REMOVED)
- Extended StaffPermission (MANAGE_DOCUMENTS)
- Extended NotificationType (BOARD_TERM_EXPIRING)
- DocumentService: upload, list, download, delete, storage usage
- BoardService: positions CRUD, elect/remove members, current/history
- DocumentController: multipart upload, filtered list, download, delete, portal
- BoardController: positions, elect, remove, current board, history, portal

Frontend:
- documents.ts + board.ts service layers
- Admin /documents page: grouped by category, upload dialog, filter, download/delete
- Admin /board page: current board cards, position management, elect member dialog
- Navigation: added Dokumente + Vorstand to sidebar
- i18n: documents.* + board.* keys in de.json + en.json

cannamanage-frontend/src/services/documents.ts

@@ -0,0 +1,108 @@
+import { apiClient } from "@/lib/api-client"
+
+export type DocumentCategory =
+  | "SATZUNG"
+  | "PROTOKOLL"
+  | "VERTRAG"
+  | "VERSICHERUNG"
+  | "GENEHMIGUNG"
+  | "SONSTIGES"
+
+export type DocumentAccessLevel = "ALL_MEMBERS" | "BOARD_ONLY"
+
+export interface ClubDocument {
+  id: string
+  title: string
+  category: DocumentCategory
+  filename: string
+  contentType: string
+  fileSize: number
+  accessLevel: DocumentAccessLevel
+  description: string | null
+  uploadedBy: string
+  createdAt: string
+  updatedAt: string | null
+}
+
+export interface StorageUsage {
+  bytesUsed: number
+}
+
+export async function uploadDocument(
+  clubId: string,
+  title: string,
+  category: DocumentCategory,
+  accessLevel: DocumentAccessLevel,
+  description: string | null,
+  file: File
+): Promise<ClubDocument> {
+  const formData = new FormData()
+  formData.append("file", file)
+
+  const params = new URLSearchParams({
+    clubId,
+    title,
+    category,
+    accessLevel,
+  })
+  if (description) params.append("description", description)
+
+  // Multipart upload — use raw fetch since apiClient assumes JSON
+  const res = await fetch(
+    `/api/backend/documents/upload?${params.toString()}`,
+    {
+      method: "POST",
+      body: formData,
+    }
+  )
+  if (!res.ok) throw new Error("Upload failed")
+  return res.json()
+}
+
+export function listDocuments(
+  clubId: string,
+  category?: DocumentCategory,
+  accessLevel?: DocumentAccessLevel
+): Promise<ClubDocument[]> {
+  const params = new URLSearchParams({ clubId })
+  if (category) params.append("category", category)
+  if (accessLevel) params.append("accessLevel", accessLevel)
+  return apiClient<ClubDocument[]>(`/documents?${params.toString()}`)
+}
+
+export async function downloadDocument(id: string): Promise<Blob> {
+  const res = await fetch(`/api/backend/documents/${id}/download`)
+  if (!res.ok) throw new Error("Download failed")
+  return res.blob()
+}
+
+export function deleteDocument(id: string, clubId: string): Promise<void> {
+  return apiClient<void>(`/documents/${id}?clubId=${clubId}`, {
+    method: "DELETE",
+  })
+}
+
+export function getStorageUsage(clubId: string): Promise<StorageUsage> {
+  return apiClient<StorageUsage>(`/documents/usage?clubId=${clubId}`)
+}
+
+export function getPortalDocuments(clubId: string): Promise<ClubDocument[]> {
+  return apiClient<ClubDocument[]>(`/portal/documents?clubId=${clubId}`)
+}
+
+// Helper: format file size
+export function formatFileSize(bytes: number): string {
+  if (bytes < 1024) return `${bytes} B`
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`
+  return `${(bytes / (1024 * 1024)).toFixed(1)} MB`
+}
+
+// Category labels
+export const categoryLabels: Record<DocumentCategory, string> = {
+  SATZUNG: "Satzung",
+  PROTOKOLL: "Protokoll",
+  VERTRAG: "Vertrag",
+  VERSICHERUNG: "Versicherung",
+  GENEHMIGUNG: "Genehmigung",
+  SONSTIGES: "Sonstiges",
+}