feat: Implement NotificationsView component for Lendair iOS

- Create NotificationsView.swift with SwiftUI List and pull-to-refresh
- Create NotificationRowView.swift for individual notification items
- Create NotificationsViewModel.swift with MVVM pattern
- Implement empty state view for no notifications
- Add mark-as-read and mark-all-as-read functionality
- Support notification types: loan approved/rejected, payment received/due, new lender, system updates
- Add toolbar action for marking all notifications as read
- Include README.md with architecture documentation and integration guide

Next: Connect tRPC notifications router for data fetching

Lendair/ViewModels/NotificationsViewModel.swift

@@ -0,0 +1,137 @@
+import Foundation
+import SwiftUI
+
+@MainActor
+class NotificationsViewModel: ObservableObject {
+    @Published var notifications: [NotificationItem] = []
+    @Published var isLoading: Bool = false
+    @Published var lastRefreshDate: Date?
+    
+    private let notificationsService: NotificationsService
+    
+    init(notificationsService: NotificationsService = NotificationsService()) {
+        self.notificationsService = notificationsService
+    }
+    
+    func fetchNotifications() async {
+        isLoading = true
+        defer {
+            isLoading = false
+            lastRefreshDate = Date()
+        }
+        
+        do {
+            let fetchedNotifications = try await notificationsService.list()
+            notifications = fetchedNotifications.sorted { $0.createdAt > $1.createdAt }
+        } catch {
+            print("Failed to fetch notifications: \(error)")
+        }
+    }
+    
+    func refresh() async {
+        await fetchNotifications()
+    }
+    
+    func markAsRead(id: String) async {
+        guard let index = notifications.firstIndex(where: { $0.id == id }) else { return }
+        
+        do {
+            try await notificationsService.markAsRead(id: id)
+            notifications[index].isRead = true
+        } catch {
+            print("Failed to mark notification as read: \(error)")
+        }
+    }
+    
+    func markAllAsRead() async {
+        let unreadIds = notifications.filter { !$0.isRead }.map { $0.id }
+        guard !unreadIds.isEmpty else { return }
+        
+        do {
+            try await notificationsService.markAllAsRead()
+            for index in notifications.indices {
+                notifications[index].isRead = true
+            }
+        } catch {
+            print("Failed to mark all as read: \(error)")
+        }
+    }
+    
+    var unreadCount: Int {
+        notifications.filter { !$0.isRead }.count
+    }
+}
+
+struct NotificationItem: Identifiable, Equatable {
+    let id: String
+    let type: NotificationType
+    let title: String
+    let message: String
+    let createdAt: Date
+    var isRead: Bool
+    
+    static func == (lhs: NotificationItem, rhs: NotificationItem) -> Bool {
+        lhs.id == rhs.id && lhs.isRead == rhs.isRead
+    }
+}
+
+enum NotificationType: String, CaseIterable {
+    case loanApproved = "LOAN_APPROVED"
+    case loanRejected = "LOAN_REJECTED"
+    case paymentReceived = "PAYMENT_RECEIVED"
+    case paymentDue = "PAYMENT_DUE"
+    case newLender = "NEW_LENDER"
+    case systemUpdate = "SYSTEM_UPDATE"
+    
+    var icon: String {
+        switch self {
+        case .loanApproved:
+            return "checkmark.circle.fill"
+        case .loanRejected:
+            return "xmark.circle.fill"
+        case .paymentReceived:
+            return "arrow.down.circle.fill"
+        case .paymentDue:
+            return "exclamationmark.circle.fill"
+        case .newLender:
+            return "person.circle.fill"
+        case .systemUpdate:
+            return "info.circle.fill"
+        }
+    }
+    
+    var color: Color {
+        switch self {
+        case .loanApproved:
+            return .green
+        case .loanRejected:
+            return .red
+        case .paymentReceived:
+            return .green
+        case .paymentDue:
+            return .orange
+        case .newLender:
+            return .blue
+        case .systemUpdate:
+            return .gray
+        }
+    }
+}
+
+class NotificationsService {
+    func list() async throws -> [NotificationItem] {
+        // TODO: Connect to tRPC notifications router
+        // let result = await APIClient.shared.query("notifications.list")
+        return []
+    }
+    
+    func markAsRead(id: String) async throws {
+        // TODO: Connect to tRPC notifications router
+        // try await APIClient.shared.mutation("notifications.markAsRead", { id })
+    }
+    
+    func markAllAsRead() async throws {
+        // TODO: Connect to tRPC notifications router
+        // try await APIClient.shared.mutation("notifications.markAllAsRead", {})
+    }
+}