fix: Address code review findings for NotificationsView (FRE-4737)

- P0: Add default param to protocol list(params:) for compile fix
- P1: Fix onDelete async closure, implement deletion logic
- P2: Remove redundant objectWillChange.send() (Published handles it)
- P2: Make RelativeDateTimeFormatter static singleton (per-row perf)
- P3: Replace deprecated NavigationView with NavigationStack

Lendair/ViewModels/NotificationsViewModel.swift

@@ -54,7 +54,6 @@ class NotificationsViewModel: ObservableObject {
             try await notificationsService.markAsRead(id: id)
             notifications[index].isRead = true
             badgeCount = max(0, badgeCount - 1)
-            objectWillChange.send()
         } catch {
             print("Failed to mark notification as read: \(error)")
         }
@@ -70,7 +69,6 @@ class NotificationsViewModel: ObservableObject {
                 notifications[index].isRead = true
             }
             badgeCount = 0
-            objectWillChange.send()
         } catch {
             print("Failed to mark all as read: \(error)")
         }