add PHPCS and Stylelint environment, test in CI, ignore from deployment

Verify compliance to coding standards in GH action.
The necessary environment files should not be deployed, so the deployment
action explicitly uses the .distignore file to exclude them.

.distignore

@@ -0,0 +1,12 @@
+/.git
+/.github
+/node_modules
+/vendor
+/.distignore
+/.gitignore
+/.stylelintrc.json
+/composer.json
+/composer.lock
+/package.json
+/package-lock.json
+/phpcs.xml

.github/workflows/test.yml

@@ -0,0 +1,24 @@
+name: Tests
+on: [push, pull_request]
+jobs:
+  quality:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '8.0'
+          tools: composer
+      - name: Setup Node
+        uses: actions/setup-node@v3
+        with:
+          node-version: '18'
+      - name: Code style checks for PHP
+        run: |
+          composer install
+          composer lint-php
+      - name: Code style checks for SCSS
+        run: |
+          npm ci
+          npm run lint-scss

.gitignore

@@ -0,0 +1,4 @@
+/.idea
+/*.css
+/node_modules
+/vendor

.stylelintrc.json

@@ -0,0 +1,8 @@
+{
+  "extends": "@wordpress/stylelint-config/scss",
+  "rules": {
+    "max-line-length": null,
+    "no-descending-specificity": null,
+    "value-keyword-case": null
+  }
+}

composer.json

@@ -0,0 +1,44 @@
+{
+  "name": "pluginkollektiv/lovelace",
+  "type": "wordpress-theme",
+  "license": "GPL-2.0+",
+  "description": "Atomic Blocks child theme for pluginkollektiv.org",
+  "homepage": "https://pluginkollektiv.org/",
+  "authors": [
+    {
+      "name": "pluginkollektiv",
+      "homepage": "https://github.com/pluginkollektiv"
+    }
+  ],
+  "keywords": [
+    "wordpress", "wordpress-theme"
+  ],
+  "support": {
+    "issues": "https://github.com/pluginkollektiv/lovelace",
+    "forum": "https://wordpress.org/support/plugin/lovelace"
+  },
+  "require": {
+    "php": ">=5.6.0",
+    "composer/installers": "^v1.12.0"
+  },
+  "require-dev": {
+    "dealerdirect/phpcodesniffer-composer-installer": "^v0.7.2",
+    "squizlabs/php_codesniffer": "^3.7.1",
+    "phpcompatibility/phpcompatibility-wp": "^2.1.4",
+    "wp-coding-standards/wpcs": "^2.3.0"
+  },
+  "scripts": {
+    "lint-css": [
+      "npx stylelint assets/scss"
+    ],
+    "lint-php": [
+      "phpcs --standard=phpcs.xml -s"
+    ]
+  },
+  "config": {
+    "allow-plugins": {
+      "composer/installers": true,
+      "dealerdirect/phpcodesniffer-composer-installer": true
+    }
+  }
+}