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

.github/workflows/ios.yml

@@ -0,0 +1,45 @@
+# iOS CI skeleton (T-iOS-1). T-iOS-16 hardens this: real Node-server
+# integration tests + the per-package 80% coverage gate (PLAN_IOS_CLIENT §9).
+name: ios
+
+on:
+  push:
+    paths:
+      - "ios/**"
+      - ".github/workflows/ios.yml"
+  pull_request:
+    paths:
+      - "ios/**"
+      - ".github/workflows/ios.yml"
+
+jobs:
+  package-tests:
+    runs-on: macos-15
+    strategy:
+      fail-fast: false
+      matrix:
+        package: [WireProtocol, SessionCore, HostRegistry, APIClient]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Select Xcode 16.3
+        run: sudo xcode-select -s /Applications/Xcode_16.3.app/Contents/Developer
+      - name: swift test (${{ matrix.package }})
+        run: swift test --package-path ios/Packages/${{ matrix.package }}
+
+  app-build:
+    runs-on: macos-15
+    steps:
+      - uses: actions/checkout@v4
+      - name: Select Xcode 16.3
+        run: sudo xcode-select -s /Applications/Xcode_16.3.app/Contents/Developer
+      - name: Install XcodeGen
+        run: brew install xcodegen
+      - name: Generate project
+        run: cd ios && xcodegen generate
+      - name: Build (iPhone 16 simulator)
+        run: |
+          xcodebuild -project ios/WebTerm.xcodeproj -scheme WebTerm \
+            -destination 'platform=iOS Simulator,name=iPhone 16' \
+            CODE_SIGNING_ALLOWED=NO build
+      - name: swift test (IntegrationTests scaffold)
+        run: swift test --package-path ios/IntegrationTests