chore: update PayPal donation link

Change PayPal donation link from paypal.me/biblicalguide to paypal.me/andupetcu

Updated in both "Join the Mission" sections on the landing page.

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

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

app/[locale]/page.tsx

@@ -379,7 +379,7 @@ export default function Home() {
               '&:hover': { bgcolor: 'primary.dark' },
             }}
             startIcon={<span style={{ fontSize: '1.5rem' }}>💳</span>}
-            href="https://paypal.me/biblicalguide"
+            href="https://paypal.me/andupetcu"
             target="_blank"
           >
             Donate via PayPal
@@ -542,7 +542,7 @@ export default function Home() {
               '&:hover': { bgcolor: 'primary.dark' },
             }}
             startIcon={<span style={{ fontSize: '1.5rem' }}>💳</span>}
-            href="https://paypal.me/biblicalguide"
+            href="https://paypal.me/andupetcu"
             target="_blank"
           >
             Donate via PayPal