Fix Express 5 wildcard route crash

Express 5 requires named wildcard params — '*' is invalid, use '*splat'.
This was causing the container to crash-loop on startup.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DReRqHxSYuVfCzTzQGD9hZ

server.js

@@ -55,7 +55,7 @@ app.delete('/api/prayers/:id', (req, res) => {
 });
 
 // Serve React for all other routes
-app.get('*', (req, res) => {
+app.get('*splat', (req, res) => {
   res.sendFile(path.join(__dirname, 'build', 'index.html'));
 });