Add Buy Me a Coffee support section

Added Buy Me a Coffee badges and links to READMEs, welcome modal, and app footer to allow users to support the project development.

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

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/components/App/App.tsx

@@ -122,6 +122,16 @@ export function App() {
       <footer className={styles.footer}>
         <span>Pedigree Draw - For genetic counselors and bioinformatics professionals</span>
         <span>NSGC Standard Symbols</span>
+        <span>
+          <a
+            href="https://buymeacoffee.com/gbanyan"
+            target="_blank"
+            rel="noopener noreferrer"
+            style={{ color: '#FFDD00', textDecoration: 'none', fontWeight: '500' }}
+          >
+            ☕ Support this project
+          </a>
+        </span>
       </footer>
 
       {showWelcome && <WelcomeModal onClose={handleCloseWelcome} />}