ci: add GitHub Actions test workflow

Runs unit tests on push to main and PRs, with caching, concurrency
control, minimal permissions, and pinned action versions.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: nficano

.github/workflows/test.yml

@@ -0,0 +1,89 @@
+# CI for php-sdk.
+#
+# Action pinning policy:
+#   - First-party actions (actions/*) are pinned to a major tag (e.g. @v4).
+#   - Third-party actions are pinned to a full commit SHA, with the released
+#     version recorded in a trailing comment for human review.
+name: test
+
+on:
+  push:
+    branches: [main]
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+      - 'LICENSE'
+      - '.gitignore'
+      - '.editorconfig'
+  pull_request:
+    branches: [main]
+    paths-ignore:
+      - '**.md'
+      - 'docs/**'
+      - 'LICENSE'
+      - '.gitignore'
+      - '.editorconfig'
+  workflow_dispatch:
+
+concurrency:
+  group: ${{ github.workflow }}-${{ github.ref }}
+  cancel-in-progress: ${{ github.event_name == 'pull_request' }}
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    name: PHP ${{ matrix.php }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php: ['8.4']
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          fetch-depth: 1
+
+      - name: Setup PHP ${{ matrix.php }}
+        uses: shivammathur/setup-php@accd6127cb78bee3e8082180cb391013d204ef9f # 2.37.0
+        with:
+          php-version: ${{ matrix.php }}
+          extensions: pdo, pdo_sqlite, mbstring, json
+          coverage: none
+          tools: composer:v2
+
+      - name: Get composer cache directory
+        id: composer-cache
+        run: echo "dir=$(composer config cache-files-dir)" >> "$GITHUB_OUTPUT"
+
+      - name: Cache composer dependencies
+        uses: actions/cache@v4
+        with:
+          path: ${{ steps.composer-cache.outputs.dir }}
+          key: ${{ runner.os }}-php-${{ matrix.php }}-composer-${{ hashFiles('**/composer.lock', '**/composer.json') }}
+          restore-keys: |
+            ${{ runner.os }}-php-${{ matrix.php }}-composer-
+
+      - name: Install dependencies
+        run: composer install --no-progress --no-interaction --prefer-dist
+
+      - name: Lint (php-cs-fixer dry-run)
+        if: hashFiles('.php-cs-fixer.dist.php', '.php-cs-fixer.php') != ''
+        run: vendor/bin/php-cs-fixer fix --dry-run --diff
+
+      - name: Run PHPUnit
+        run: vendor/bin/phpunit
+
+      - name: Upload test artifacts on failure
+        if: failure()
+        uses: actions/upload-artifact@v4
+        with:
+          name: test-artifacts-php-${{ matrix.php }}
+          path: |
+            .phpunit.cache/
+            build/
+            coverage.xml
+          if-no-files-found: ignore
+          retention-days: 7