chore(ci): add codecov config and GitHub build workflow

Add codecov.yml for coverage reporting with targets and exclusions.
Create GitHub Actions workflow to build, test, and verify Swift 6.2.0 on macOS.

Author: hanrw

.github/workflows/build.yml

@@ -0,0 +1,43 @@
+name: Build and Test
+
+# Swift 6.2 Required
+# Uses swift-actions/setup-swift to install Swift 6.2.0 regardless of runner's default version
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  build:
+    name: Build and Test
+    runs-on: macos-26
+
+    permissions:
+      contents: read
+      packages: read
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v4
+
+    - name: Setup Swift 6.2
+      uses: SwiftyLab/setup-swift@latest
+      with:
+        swift-version: "6.2.0"
+
+    - name: Get Swift version
+      run: swift --version
+
+    - name: Resolve dependencies
+      run: swift package resolve
+
+    - name: Build
+      run: swift build
+
+    - name: Run tests
+      run: swift test --parallel
+
+    - name: Build for release
+      run: swift build -c release

codecov.yml

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+coverage:
+  status:
+    project:
+      default:
+        target: 80%
+        threshold: 2%
+    patch:
+      default:
+        target: 70%
+
+comment:
+  layout: "reach,diff,flags,tree"
+  behavior: default
+  require_changes: false
+
+ignore:
+  - "**/*Preview*.swift"  # SwiftUI previews
+  - "**/TestHelpers/**/*"