Initial commit: Site Builder with PHP API backend

Visual drag-and-drop website builder using GrapesJS with:
- Multi-page editor with live preview
- File-based asset storage via PHP API (no localStorage base64)
- Template library, Docker support, and Playwright test suite

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

package.json

@@ -0,0 +1,19 @@
+{
+  "name": "site-builder",
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "directories": {
+    "doc": "docs"
+  },
+  "scripts": {
+    "test": "npx playwright test",
+    "test:headed": "npx playwright test --headed"
+  },
+  "keywords": [],
+  "author": "",
+  "license": "ISC",
+  "devDependencies": {
+    "@playwright/test": "^1.58.2"
+  }
+}