feat: Complete deletion requests management UI implementation

- Backend API:
  - Added DeletionRequestSerializer and DeletionRequestActionSerializer
  - Added DeletionRequestViewSet with approve/reject/pending_count actions
  - Added /api/deletion_requests/ route

- Frontend:
  - Created deletion-request data model
  - Created deletion-request.service.ts with full CRUD operations
  - Created DeletionRequestsComponent with status filtering (pending/approved/rejected/completed)
  - Created DeletionRequestDetailComponent with impact analysis display
  - Added /deletion-requests route with permissions guard
  - Implemented approve/reject modals with confirmation
  - Added status badges and pending request counter

- All code linted and built successfully

Co-authored-by: dawnsystem <42047891+dawnsystem@users.noreply.github.com>

src-ui/src/app/data/deletion-request.ts

@@ -0,0 +1,50 @@
+import { ObjectWithId } from './object-with-id'
+
+export interface DeletionRequestDocument {
+  id: number
+  title: string
+  created: string
+  correspondent?: string
+  document_type?: string
+  tags: string[]
+}
+
+export interface DeletionRequestImpactSummary {
+  document_count: number
+  documents: DeletionRequestDocument[]
+  affected_tags: string[]
+  affected_correspondents: string[]
+  affected_types: string[]
+  date_range?: {
+    earliest: string
+    latest: string
+  }
+}
+
+export enum DeletionRequestStatus {
+  Pending = 'pending',
+  Approved = 'approved',
+  Rejected = 'rejected',
+  Cancelled = 'cancelled',
+  Completed = 'completed',
+}
+
+export interface DeletionRequest extends ObjectWithId {
+  created_at: string
+  updated_at: string
+  requested_by_ai: boolean
+  ai_reason: string
+  user: number
+  user_username: string
+  status: DeletionRequestStatus
+  documents: number[]
+  documents_detail: DeletionRequestDocument[]
+  document_count: number
+  impact_summary: DeletionRequestImpactSummary
+  reviewed_at?: string
+  reviewed_by?: number
+  reviewed_by_username?: string
+  review_comment?: string
+  completed_at?: string
+  completion_details?: any
+}