Add baseline quality checks (#357)

.github/workflows/quality.yml

@@ -0,0 +1,49 @@
+name: Quality
+
+on:
+  pull_request:
+  push:
+    branches:
+      - master
+
+permissions:
+  contents: read
+
+jobs:
+  php:
+    name: PHP ${{ matrix.php }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        php:
+          - "8.3"
+          - "8.4"
+          - "8.5"
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php }}
+          coverage: none
+
+      - name: Check PHP syntax and regression tests
+        run: ./scripts/check.sh php
+
+  compose:
+    name: Docker Compose
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+
+      - name: Validate Compose configuration
+        run: ./scripts/check.sh compose
+
+      - name: Run shell contract tests
+        run: ./scripts/check.sh shell