feat: implement comprehensive blog system

Add dual-source blog system with Editor.js integration:
- Blog storage supporting repo-based (JSON) and database sources
- Admin panel with rich text editor using Editor.js
- Public news page with infinite scroll
- Individual blog post viewer page
- Categories management in admin
- Image upload functionality
- 4 SEO blog posts about WordPress with PluginCompass promotion
- 3 News blog posts about Plugin Compass
- API endpoints for CRUD operations
- Security and validation for admin operations

Closes blog feature request

chat/public/admin.html

@@ -45,6 +45,7 @@
         <a class="ghost" href="/admin/resources">Resources</a>
         <a class="ghost" href="/admin/external-testing">External Testing</a>
         <a class="ghost" href="/admin/contact-messages">Contact Messages</a>
+        <a class="ghost" href="/admin/blogs">Blog Management</a>
         <a class="ghost" href="/admin/login">Login</a>
       </div>
     </aside>