feat: reporting dashboard — case stats, deadline compliance, workload, billing (P1)

Backend:
- ReportingService with aggregation queries (CTEs, FILTER clauses)
- 4 API endpoints: /api/reports/{cases,deadlines,workload,billing}
- Date range filtering via ?from=&to= query params

Frontend:
- /berichte page with 4 tabs: Akten, Fristen, Auslastung, Abrechnung
- recharts: bar/pie/line charts for all report types
- Date range picker, CSV export, print-friendly view
- Sidebar nav entry with BarChart3 icon

Also resolves merge conflicts between role-based, notification, and
audit trail branches, and adds missing TS types (AuditLogResponse,
Notification, NotificationPreferences).

backend/internal/router/router.go

@@ -29,14 +29,8 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	deadlineRuleSvc := services.NewDeadlineRuleService(db)
 	calculator := services.NewDeadlineCalculator(holidaySvc)
 	storageCli := services.NewStorageClient(cfg.SupabaseURL, cfg.SupabaseServiceKey)
-<<<<<<< HEAD
 	documentSvc := services.NewDocumentService(db, storageCli, auditSvc)
-||||||| 82878df
-	documentSvc := services.NewDocumentService(db, storageCli)
-=======
-	documentSvc := services.NewDocumentService(db, storageCli)
 	assignmentSvc := services.NewCaseAssignmentService(db)
->>>>>>> mai/pike/p0-role-based
 
 	// AI service (optional — only if API key is configured)
 	var aiH *handlers.AIHandler
@@ -50,6 +44,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 
 	noteSvc := services.NewNoteService(db, auditSvc)
 	dashboardSvc := services.NewDashboardService(db)
+	reportingSvc := services.NewReportingService(db)
 
 	// Notification handler (optional — nil in tests)
 	var notifH *handlers.NotificationHandler
@@ -67,6 +62,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	ruleH := handlers.NewDeadlineRuleHandlers(deadlineRuleSvc)
 	calcH := handlers.NewCalculateHandlers(calculator, deadlineRuleSvc)
 	dashboardH := handlers.NewDashboardHandler(dashboardSvc)
+	reportH := handlers.NewReportHandler(reportingSvc)
 	noteH := handlers.NewNoteHandler(noteSvc)
 	eventH := handlers.NewCaseEventHandler(db)
 	docH := handlers.NewDocumentHandler(documentSvc)
@@ -162,16 +158,16 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 	// Dashboard — all can view
 	scoped.HandleFunc("GET /api/dashboard", dashboardH.Get)
 
-<<<<<<< HEAD
+	// Reports — all can view
+	scoped.HandleFunc("GET /api/reports/cases", reportH.Cases)
+	scoped.HandleFunc("GET /api/reports/deadlines", reportH.Deadlines)
+	scoped.HandleFunc("GET /api/reports/workload", reportH.Workload)
+	scoped.HandleFunc("GET /api/reports/billing", reportH.Billing)
+
 	// Audit log
 	scoped.HandleFunc("GET /api/audit-log", auditH.List)
 
-	// Documents
-||||||| 82878df
-	// Documents
-=======
 	// Documents — all can upload, delete checked in handler (own vs all)
->>>>>>> mai/pike/p0-role-based
 	scoped.HandleFunc("GET /api/cases/{id}/documents", docH.ListByCase)
 	scoped.HandleFunc("POST /api/cases/{id}/documents", perm(auth.PermUploadDocuments, docH.Upload))
 	scoped.HandleFunc("GET /api/documents/{docId}", docH.Download)
@@ -185,7 +181,6 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 		scoped.HandleFunc("POST /api/ai/summarize-case", perm(auth.PermAIExtraction, aiLimiter.LimitFunc(aiH.SummarizeCase)))
 	}
 
-<<<<<<< HEAD
 	// Notifications
 	if notifH != nil {
 		scoped.HandleFunc("GET /api/notifications", notifH.List)
@@ -196,12 +191,7 @@ func New(db *sqlx.DB, authMW *auth.Middleware, cfg *config.Config, calDAVSvc *se
 		scoped.HandleFunc("PUT /api/notification-preferences", notifH.UpdatePreferences)
 	}
 
-	// CalDAV sync endpoints
-||||||| 82878df
-	// CalDAV sync endpoints
-=======
 	// CalDAV sync endpoints — settings permission required
->>>>>>> mai/pike/p0-role-based
 	if calDAVSvc != nil {
 		calDAVH := handlers.NewCalDAVHandler(calDAVSvc)
 		scoped.HandleFunc("POST /api/caldav/sync", perm(auth.PermManageSettings, calDAVH.TriggerSync))