Initial scaffold — NASBackup iOS app

Full project scaffold: XcodeGen project.yml, Core models/protocols/errors,
SMBService (kishikawakatsumi/SMBClient), SFTPService (Citadel 0.9.2),
PhotoLibraryService, LANMonitor, BackupEngine, BackgroundTaskManager,
all feature UIs (Login, Connect, Browse, Backup, History, Settings),
Shared components and theme. Builds clean with zero errors.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Core/Models/NASConnection.swift

@@ -0,0 +1,42 @@
+import Foundation
+
+enum NASProtocol: String, Codable, CaseIterable {
+    case smb  = "SMB"
+    case sftp = "SFTP"
+
+    var defaultPort: Int {
+        switch self {
+        case .smb:  return 445
+        case .sftp: return 22
+        }
+    }
+}
+
+struct NASConnection: Codable, Identifiable, Equatable {
+    var id: UUID = UUID()
+    var host: String
+    var port: Int
+    var nasProtocol: NASProtocol
+    var username: String
+    var password: String
+    var remotePath: String
+    var displayName: String
+
+    init(
+        host: String,
+        port: Int? = nil,
+        nasProtocol: NASProtocol = .smb,
+        username: String,
+        password: String,
+        remotePath: String = "/",
+        displayName: String = ""
+    ) {
+        self.host = host
+        self.port = port ?? nasProtocol.defaultPort
+        self.nasProtocol = nasProtocol
+        self.username = username
+        self.password = password
+        self.remotePath = remotePath
+        self.displayName = displayName.isEmpty ? host : displayName
+    }
+}