feat: add third-party proxy mode and improve onboarding

Shared/ProxyRuntimeMode.swift

@@ -0,0 +1,49 @@
+import Foundation
+
+enum ProxyRuntimeMode: String, CaseIterable, Codable, Identifiable {
+    case localWiFi
+    case thirdParty
+
+    var id: String { rawValue }
+
+    var displayName: String {
+        switch self {
+        case .localWiFi: return "APP模式"
+        case .thirdParty: return "第三方代理模式"
+        }
+    }
+}
+
+@MainActor
+final class ProxyRuntimeModeStore: ObservableObject {
+    static let shared = ProxyRuntimeModeStore()
+
+    private enum Key {
+        static let runtimeMode = "proxyRuntimeMode"
+        static let hasSelectedRuntimeMode = "hasSelectedProxyRuntimeMode"
+    }
+
+    @Published private(set) var mode: ProxyRuntimeMode
+    @Published private(set) var hasSelectedMode: Bool
+    private let defaults: UserDefaults
+
+    init(defaults: UserDefaults = AppGroup.defaults) {
+        self.defaults = defaults
+        self.mode = defaults.string(forKey: Key.runtimeMode)
+            .flatMap(ProxyRuntimeMode.init(rawValue:)) ?? .localWiFi
+        self.hasSelectedMode = defaults.bool(forKey: Key.hasSelectedRuntimeMode)
+    }
+
+    func setMode(_ mode: ProxyRuntimeMode) {
+        let changed = self.mode != mode
+        self.mode = mode
+        hasSelectedMode = true
+        defaults.set(mode.rawValue, forKey: Key.runtimeMode)
+        defaults.set(true, forKey: Key.hasSelectedRuntimeMode)
+        if changed {
+            RuntimeLogger.info("APP", "Mode", "代理运行模式已切换", details: [
+                "模式": mode.displayName
+            ])
+        }
+    }
+}