feat(ios): W0 scaffold + day-1 spike + WireProtocol frozen contract + TestSupport doubles

T-iOS-1: ios/ XcodeGen project (iOS 17, Swift 6 strict concurrency, ATS per PLAN §5.2), 5 SPM package shells, CI skeleton
T-iOS-2: Origin spike vs real server — URLSessionWebSocketTask custom Origin CONFIRMED (no Starscream); 16MiB replay + EMSGSIZE(40) errno correction written back to plan
T-iOS-3: WireProtocol frozen contract, 59 tests, 100% line coverage, cross-impl vectors vs src/protocol.ts via tsx
T-iOS-4: FakeTransport/FakeClock/FakeHTTPTransport doubles
Verify: independent agent re-ran all acceptance — 6/6 PASS

ios/App/WebTerm/Screens/SpikeTerminalScreen.swift

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+//
+// SpikeTerminalScreen.swift — T-iOS-2 Day-1 spike ②【临时文件，W4/T-iOS-15 删除】
+//
+// 目的：SwiftTerm TerminalView 的真机键盘/IME smoke 载体（plan §7 T-iOS-2）：
+//   - 键盘弹出 / first-responder 行为
+//   - 中文 IME 组合输入（不自加 keydown 监听，组合事件全交系统栈）
+//   - inputAccessoryView 上 Esc/Ctrl-C 可发 —— SwiftTerm iOS 端自带
+//     TerminalAccessory（含 esc/ctrl/tab 键，iOSAccessoryView.swift），
+//     spike 直接用它验证；正式 key-bar（逐字节复刻 public/keybar.ts）归 T-iOS-11
+//   - 文本选择不崩（SwiftTerm 自绘选择是历史坑点）
+//
+// 接线为【纯本地回显】（无服务器依赖）：typed bytes → send() → feed() 原样喂回，
+// CR 扩成 CRLF。真实 SessionEngine 接线是 W2/W3 的事。
+//
+// 2026-07-04：无可用真机 —— 真机清单各项记 DEFERRED(真机不可用)（见 PROGRESS_LOG
+// 条目）。本文件当下的验收是：作为 App target 源码在模拟器 xcodebuild 构建通过。
+
+import SwiftTerm
+import SwiftUI
+
+/// Day-1 spike 的最小 SwiftUI 壳。不接入 WebTermApp 导航（WebTermApp.swift 归
+/// T-iOS-1/T-iOS-15 所有）；存在本身即证明 App target 在 Swift 6 strict
+/// concurrency 下能链接并承载 SwiftTerm 的 TerminalView。
+struct SpikeTerminalScreen: View {
+    var body: some View {
+        LocalEchoTerminal()
+            .ignoresSafeArea(.container, edges: .bottom)
+            .navigationTitle("SwiftTerm spike")
+    }
+}
+
+/// 承载 SwiftTerm UIKit `TerminalView` 的 UIViewRepresentable，接本地回显。
+/// 形状即 T-iOS-11 正式 TerminalScreen 的雏形（去掉 SessionEngine）。
+private struct LocalEchoTerminal: UIViewRepresentable {
+    func makeCoordinator() -> LocalEchoCoordinator {
+        LocalEchoCoordinator()
+    }
+
+    func makeUIView(context: Context) -> TerminalView {
+        let view = TerminalView(frame: .zero)
+        view.terminalDelegate = context.coordinator
+        view.feed(text: SpikeGreeting.text)
+        return view
+    }
+
+    func updateUIView(_ uiView: TerminalView, context: Context) {
+        // 本地回显无外部状态可同步。
+    }
+}
+
+private enum SpikeGreeting {
+    /// 行尾用 CRLF：PTY 语义下裸 LF 只下移一行不回车。
+    static let text = "SwiftTerm local-echo spike (T-iOS-2)\r\n"
+        + "Typed bytes are echoed locally; CR -> CRLF.\r\n"
+        + "真机清单: 键盘弹出 / 中文 IME / accessory esc·ctrl / 文本选择\r\n\r\n> "
+}
+
+/// 本地回显 delegate：SwiftTerm 要"发给宿主"的每个字节原样喂回终端。
+/// Enter 产生的 CR（0x0D）补一个 LF，光标才会回行首并换行。
+@MainActor
+private final class LocalEchoCoordinator: NSObject, @preconcurrency TerminalViewDelegate {
+    private static let carriageReturn: UInt8 = 0x0D
+    private static let lineFeed: UInt8 = 0x0A
+
+    func send(source: TerminalView, data: ArraySlice<UInt8>) {
+        var echoed: [UInt8] = []
+        echoed.reserveCapacity(data.count + 1)
+        for byte in data {
+            echoed.append(byte)
+            if byte == Self.carriageReturn {
+                echoed.append(Self.lineFeed)
+            }
+        }
+        source.feed(byteArray: echoed[...])
+    }
+
+    func sizeChanged(source: TerminalView, newCols: Int, newRows: Int) {}
+    func setTerminalTitle(source: TerminalView, title: String) {}
+    func hostCurrentDirectoryUpdate(source: TerminalView, directory: String?) {}
+    func scrolled(source: TerminalView, position: Double) {}
+    func requestOpenLink(source: TerminalView, link: String, params: [String: String]) {}
+    func clipboardCopy(source: TerminalView, content: Data) {}
+    func rangeChanged(source: TerminalView, startY: Int, endY: Int) {}
+    // bell / iTermContent 用 SwiftTerm 的默认实现。
+}
+
+#Preview {
+    SpikeTerminalScreen()
+}

ios/App/WebTerm/WebTermApp.swift

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+import SwiftUI
+
+/// T-iOS-1 scaffold: empty-window placeholder. Navigation assembly
+/// (Pairing → SessionList → Terminal) is wired in T-iOS-15.
+@main
+struct WebTermApp: App {
+    var body: some Scene {
+        WindowGroup {
+            HelloPlaceholderView()
+        }
+    }
+}
+
+private struct HelloPlaceholderView: View {
+    var body: some View {
+        VStack(spacing: 12) {
+            Image(systemName: "terminal")
+                .font(.largeTitle)
+            Text("Hello WebTerm")
+                .font(.title2)
+        }
+        .padding()
+    }
+}