Add reinstate feature for deleted files

- Add MarkNotDeleted method to repository
- Add ReinstateFile method to service
- Add AdminReinstate handler
- Add /reinstate/:id route
- Add Reinstate button in admin menu for deleted files

internal/file/routes.go

@@ -33,6 +33,7 @@ func RegisterRoutes(r *gin.RouterGroup, h *Handler) {
 
 	adminRoutes.GET("/delete/:id", h.AdminDelete)
 	adminRoutes.GET("/delete/fr/:id", h.AdminForceDelete)
+	adminRoutes.GET("/reinstate/:id", h.AdminReinstate)
 
 	adminRoutes.POST("/import", h.Import)
 	adminRoutes.GET("/export", h.Export)