feat(ipad): W1-W3 — adaptive split-view layout + finding fixes

T-iPad-2: AdaptiveRootView/LayoutPolicy (sole size-class decision), SplitRootView
(NavigationSplitView sidebar+detail), StackRootView (iPhone path verbatim, zero
regression); privacy shade hoisted to shared ZStack top for both branches
T-iPad-3: KeyBarVisibility predicate (hide when hardware keyboard present),
pointer context menu (copy/new-in-cwd/kill, all via existing channels)
T-iPad-4: Projects multi-column grid on iPad (idiom-gated), adaptive sheet detents
T-iPad-5 findings (4/4 fixed): kill onKillSession thread-through +
AppCoordinator.killCurrentSession; split route-gated to .sessions (iPad first-run
pairing); continue-last banner in split sidebar; iPad XCUITest deferred (covered
by SidebarSelectionTests)
Verified: iPhone 16 277 + iPad Pro 11 278 tests green; packages 261 + integration 10;
zero changes under ios/Packages, src/, public/

ios/App/WebTerm/Wiring/AdaptiveRootView.swift

@@ -0,0 +1,110 @@
+import SwiftUI
+
+/// T-iPad-2 · size-class 驱动的单一根视图。按 `LayoutPolicy.mode` 在 compact
+/// 宽度（iPhone / iPad Slide Over）选 `StackRootView`（现有路径，字节级不变）、
+/// 在 regular 宽度（iPad 全屏 / 大分屏 / Stage Manager 大窗）选 `SplitRootView`
+/// （分栏）。
+///
+/// **横切布线只声明一次、两分支共享**（PLAN_IOS_IPAD §5 T-iPad-2）：
+/// - 隐私遮罩：ZStack 的**最顶层**，覆盖整棵导航树（含 split detail 的终端
+///   字节）——`scenePhase != .active` 即遮（安全不变式，见 `PrivacyShadePolicy`）。
+///   上提到这里，split detail 与 stack push 同样被遮，无遗漏。
+/// - `.task` bootstrap / `.onChange(scenePhase)` / `.onOpenURL` / deep-link 提示
+///   alert / add-host sheet / Projects sheet：全部设备无关，原样从旧 `RootView`
+///   搬到这一层，故 compact 分支拿到与适配前完全一致的横切行为。
+///
+/// size class 是**运行时可变量**（iPad 拉出 Slide Over 立刻 regular→compact），
+/// 所以这不是两套 UI 分叉，而是同一次运行内的自适应切换：`terminalController`
+/// 归 `AppCoordinator` 所有，与布局分支正交，切换时不重建（T-iOS-29 `.id`
+/// 稳定性的前提）。
+struct AdaptiveRootView: View {
+    @Bindable var coordinator: AppCoordinator
+    @Environment(\.scenePhase) private var scenePhase
+    @Environment(\.horizontalSizeClass) private var horizontalSizeClass
+
+    var body: some View {
+        ZStack {
+            layoutBranch
+            if PrivacyShadePolicy.isShadeVisible(for: scenePhase) {
+                PrivacyShadeView()
+            }
+        }
+        .task { await coordinator.bootstrap() }
+        .onChange(of: scenePhase) { _, phase in
+            coordinator.handleScenePhase(phase)
+        }
+        .onOpenURL { coordinator.handleDeepLink(url: $0) } // T-iOS-22
+        .alert(DeepLinkCopy.hintTitle, isPresented: deepLinkHintBinding) {
+            Button(DeepLinkCopy.hintConfirm) { coordinator.deepLink.clearHint() }
+        } message: {
+            Text(coordinator.deepLink.hintMessage ?? "")
+        }
+        .sheet(
+            isPresented: $coordinator.isAddHostPresented,
+            onDismiss: { coordinator.addHostDismissed() }
+        ) {
+            addHostSheet
+        }
+        .sheet(
+            isPresented: $coordinator.isProjectsPresented,
+            onDismiss: { coordinator.projectsDismissed() }
+        ) {
+            projectsSheet
+        }
+    }
+
+    // MARK: - Layout branch (the SOLE size-class consumer)
+
+    @ViewBuilder private var layoutBranch: some View {
+        // Split only makes sense once we're in the session list. `.loading` and
+        // `.pairing` (genuine iPad first-run, no paired host) get the full-screen
+        // stack flow regardless of size class — a split sidebar has nothing to
+        // list yet and would strand the user on the not-paired empty state
+        // (T-iPad-5 finding). Route-gate the split branch.
+        switch LayoutPolicy.mode(horizontalSizeClass: horizontalSizeClass) {
+        case .split where coordinator.route == .sessions:
+            SplitRootView(coordinator: coordinator)
+        default:
+            StackRootView(coordinator: coordinator)
+        }
+    }
+
+    // MARK: - Deep-link hint alert (T-iOS-22)
+
+    /// unknown host / store failure 提示（同旧 `RootView`）。
+    private var deepLinkHintBinding: Binding<Bool> {
+        Binding(
+            get: { coordinator.deepLink.hintMessage != nil },
+            set: { presented in
+                guard !presented else { return }
+                coordinator.deepLink.clearHint()
+            }
+        )
+    }
+
+    // MARK: - Add-host sheet (multi-host entry, list header)
+
+    @ViewBuilder private var addHostSheet: some View {
+        if let viewModel = coordinator.addHostPairingViewModel {
+            NavigationStack {
+                PairingScreen(viewModel: viewModel) { host in
+                    coordinator.completeAddHost(host)
+                }
+            }
+        }
+    }
+
+    // MARK: - Projects sheet (T-iOS-26)
+
+    /// 自带 NavigationStack：列表 → 详情 → 差异都在 sheet 内 push；
+    /// "在此仓库开新会话" 关掉 sheet 并在根导航开终端。
+    @ViewBuilder private var projectsSheet: some View {
+        if let viewModel = coordinator.projectsViewModel {
+            NavigationStack {
+                ProjectsScreen(viewModel: viewModel) { request in
+                    coordinator.openProject(request)
+                }
+            }
+        }
+    }
+}