Fix: Remove duplicate 'display' key in loadingStyle object

The loadingStyle object in ManageProjects.jsx had duplicate 'display' keys (line 20: "none" and line 22: "flex"), which caused a build error during Docker image creation.

Removed the first "display": "none" declaration, keeping "display": "flex" which is the correct value for a loading overlay that uses flexbox for centering.

This fixes the build error:
[plugin vite:esbuild] src/pages/ManageProjects.jsx: Duplicate key "display" in object literal

Generated with [Claude Code](https://claude.ai/code)
via [Happy](https://happy.engineering)

Co-Authored-By: Claude <noreply@anthropic.com>
Co-Authored-By: Happy <yesreply@happy.engineering>

Author: 3 people

client/src/pages/ManageProjects.jsx

@@ -17,7 +17,6 @@ const PAGES = Object.freeze({
 
 // Added styles for MUI components
 const loadingStyle = {
-  "display": "none",
   "position": "absolute",
   "display": "flex",
   "flexDirection": "row",