Add GitHub Actions CI workflow

.github/workflows/ci.yml

@@ -0,0 +1,39 @@
+name: CI
+
+on:
+  pull_request:
+    branches: [main]
+
+concurrency:
+  group: ci-${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-test:
+    name: Build & Test
+    runs-on: macos-26
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v5
+
+      - name: Select Xcode 26.5 (stable)
+        id: xcode-stable
+        continue-on-error: true
+        uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: "^26.5"
+
+      - name: Select Xcode 26.5 (beta fallback)
+        if: steps.xcode-stable.outcome != 'success'
+        uses: maxim-lobanov/setup-xcode@v1
+        with:
+          xcode-version: "^26.5-beta"
+
+      - name: Swift version
+        run: swift --version
+
+      - name: Test
+        run: |
+          xcodebuild test \
+            -scheme AnalyticsKit \
+            -destination "platform=iOS Simulator,name=iPhone 17 Pro"