Adds Prettier formatting and PHP support

Adds Prettier for consistent code formatting across the project.
Includes PHP plugin and configures formatting for PHP files.
Adds format and format:check scripts to package.json for ease of use.

.prettierrc

@@ -0,0 +1,17 @@
+{
+  "tabWidth": 2,
+  "singleQuote": true,
+  "printWidth": 120,
+  "plugins": ["@prettier/plugin-php"],
+  "overrides": [
+    {
+      "files": "*.php",
+      "options": {
+        "parser": "php",
+        "tabWidth": 2,
+        "printWidth": 120,
+        "singleQuote": true
+      }
+    }
+  ]
+}