✅ Add PHPStan workflow

.github/exclude_list

@@ -1,8 +1,12 @@
 node_modules/
 src/
+composer.json
+composer.lock
 package.json
 package-lock.json
 ruleset.xml
 webpack.config.js
 *scss/
 .git*
+phpstan.neon.dist
+.phpcs.xml

.github/workflows/phpstan.yml

@@ -0,0 +1,20 @@
+name: PHPStan
+
+on: [workflow_call]
+
+jobs:
+  test-phpstan:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install composer dependencies
+        uses: php-actions/composer@v6
+      - name: PHPStan static analysis
+        uses: php-actions/phpstan@v3
+        with:
+          args: -v
+          configuration: phpstan.neon.dist
+          memory_limit: 2G
+          path: inc/ multisite-auto-language-switcher.php
+          php_version: 7.4

.github/workflows/wordpress-plugin-deploy.yml

@@ -5,8 +5,11 @@ on:
     - "*"
     - "!*-*"
 jobs:
+  tests:
+    uses: ./.github/workflows/phpstan.yml
   tag:
     name: New tag
+    needs: tests
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v4

composer.json

@@ -0,0 +1,17 @@
+{
+    "scripts": {
+      "phpstan": "phpstan analyse -v --memory-limit=2048M"
+    },
+    "require-dev": {
+        "phpstan/phpstan": "^1.12",
+        "szepeviktor/phpstan-wordpress": "^1.3",
+        "phpstan/extension-installer": "^1.4",
+        "swissspidy/phpstan-no-private": "^0.2.1",
+        "phpstan/phpstan-deprecation-rules": "^1.2"
+    },
+    "config": {
+        "allow-plugins": {
+            "phpstan/extension-installer": true
+        }
+    }
+}