feat(apple): native SwiftUI app for iOS and macOS

Add a native SwiftUI VniDrop app (Send/Receive/Settings) talking to the
Rust core via generated UniFFI Swift bindings, plus the uniffi-bindgen
helper crate. iOS uses a TabView, macOS a NavigationSplitView sidebar.

apple/VniDrop/Core/AppLogger.swift

@@ -0,0 +1,24 @@
+import Foundation
+import os
+
+/// Minimal structured logger, ported from `logging/AppLogger.kt`. Never logs
+/// tickets, endpoint ids, or file contents (callers pass only redacted fields).
+enum AppLogger {
+	private static let logger = Logger(subsystem: "com.vnidrop.app", category: "app")
+
+	static func info(_ scope: String, _ message: String, _ fields: [String: String] = [:]) {
+		logger.info("[\(scope, privacy: .public)] \(message, privacy: .public) \(fieldString(fields), privacy: .public)")
+	}
+
+	static func error(_ scope: String, _ message: String, _ error: Error? = nil) {
+		if let error {
+			logger.error("[\(scope, privacy: .public)] \(message, privacy: .public): \(error.technicalDetail, privacy: .public)")
+		} else {
+			logger.error("[\(scope, privacy: .public)] \(message, privacy: .public)")
+		}
+	}
+
+	private static func fieldString(_ fields: [String: String]) -> String {
+		fields.isEmpty ? "" : fields.map { "\($0)=\($1)" }.joined(separator: " ")
+	}
+}