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/Features/Settings/BugReportService.swift

@@ -0,0 +1,30 @@
+import Foundation
+
+/// Bug-report draft, ported from `diagnostics/BugReportService.kt`.
+struct BugReportDraft {
+	let whatHappened: String
+	let expected: String
+	let steps: String
+	let contact: String
+	let includeLogs: Bool
+}
+
+/// Bug-report submission. The full diagnostics transport (URLSession + build
+/// config) lands in the diagnostics phase; this protocol is the stable seam.
+protocol BugReportService {
+	func submit(_ draft: BugReportDraft, deviceInfo: DeviceInfo?) async -> Result<Void, Error>
+	func previewLogBytes() async -> Int
+}
+
+/// Offline-safe no-op used until the diagnostics transport is configured.
+struct NoopBugReportService: BugReportService {
+	func submit(_ draft: BugReportDraft, deviceInfo: DeviceInfo?) async -> Result<Void, Error> {
+		.failure(InvitationError.message("Bug reporting is not configured"))
+	}
+	func previewLogBytes() async -> Int { 0 }
+}
+
+/// Whether the diagnostics stack is compiled in (mirrors DiagnosticsBuildConfig).
+enum DiagnosticsBuildConfig {
+	static let included = false
+}