chore: add gray border around README screenshot

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

Author: tianzhou

README.md

@@ -10,9 +10,9 @@
   </a>
 </p>
 
-<p align="center">
+<table align="center"><tr><td>
   <img src="https://raw.githubusercontent.com/pgplex/pgconsole/main/website/public/sql-editor-overview.webp" alt="pgconsole SQL editor" />
-</p>
+</td></tr></table>
 
 **pgconsole** is web-based PostgreSQL editor. Single binary, single config file, no database required. Connect your team to PostgreSQL with access control and audit logging built in.