feat(ipad): T-iPad-1 — device family [1,2] + iPad orientations + CI leg

Opens WebTerm to iPhone + iPad: TARGETED_DEVICE_FAMILY 1→1,2 (project + all
targets), iPad gets all four orientations (~ipad key), ios.yml gains an
ipad-tests leg (iPad Pro 11 sim). Built plist verified UIDeviceFamily [1,2];
app launches natively full-screen on iPad Pro 11 sim (no letterbox). Adaptive
layout (NavigationSplitView) lands in T-iPad-2. Plan: docs/PLAN_IOS_IPAD.md.

.github/workflows/ios.yml

@@ -80,6 +80,25 @@ jobs:
             -destination 'platform=iOS Simulator,name=iPhone 16' \
             test
 
+  # iPad adaptation (T-iPad-1): run the same app suite on an iPad simulator so
+  # the adaptive layout (regular size class / NavigationSplitView, T-iPad-2) is
+  # exercised in CI, not only the compact iPhone path.
+  ipad-tests:
+    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: xcodebuild test (WebTermTests, iPad Pro 11-inch simulator)
+        run: |
+          xcodebuild -project ios/WebTerm.xcodeproj -scheme WebTerm \
+            -destination 'platform=iOS Simulator,name=iPad Pro 11-inch (M4)' \
+            test
+
   # Layer 3: contract tests against the real Node server (T-iOS-16 test list).
   # npm ci compiles node-pty (needs the Xcode toolchain — present on the
   # runner); the Swift ServerHarness then boots the server itself.