Fix download button text color to black for better readability

Change download button text from white to black for better contrast against blue background

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <[email protected]>

Author: b0ase

frontend/src/pages/EducationalProposalPage.tsx

@@ -162,7 +162,7 @@ const EducationalProposalPage: React.FC = () => {
 
           .download-button {
             background: linear-gradient(135deg, #2196f3 0%, #1976d2 100%);
-            color: #ffffff;
+            color: #000000;
             border: none;
             padding: 12px 24px;
             border-radius: 6px;