Stop crashing the server on unhandled promise rejections

A single missed .catch() anywhere in the notification code (email/WhatsApp
sending) previously took down the whole process via process.exit(1). Log
the error instead and keep running.

CHANGELOG.md

@@ -9,6 +9,7 @@ and this project follows [Semantic Versioning](https://semver.org/).
 
 ### Fixed
 
+- The server used to hard-crash (`process.exit(1)`) on any unhandled promise rejection, so a single missed error handler anywhere in the app's fire-and-forget notification code (email/WhatsApp sending) could take the whole server down. It now logs the error and keeps running.
 - Accounts created on someone's behalf (at-the-door walk-in registration, or manual registration from the Admin/Supervisor dashboard) now get their activation link (email or WhatsApp, whichever they have) sent immediately when the account is created, instead of only on their first failed login attempt — matching what the Terms of Use already promised.
 - Manual registration with a real email address used to create the account already active with a fixed, undisclosed password (`Hope123`) — the visitor had no way to know it. That account is now created inactive and gets the same immediate activation link, so the visitor sets their own password — unless a password was supplied directly (see below), in which case it's activated immediately with no link needed.
 - The self-service kiosk's "Create an account" password field never actually worked — the account was always created with a different password behind the scenes, so visitors who set one couldn't log in with it. Manual registration now honours a caller-supplied password and activates the account immediately instead of discarding it.

backend/src/index.js

@@ -1265,11 +1265,12 @@ app.listen(PORT, () => {
   }
 });
 
-// Handle unhandled promise rejections
+// Log unhandled promise rejections without killing the server, since a single
+// missed .catch() on fire-and-forget notification code (email/WhatsApp sends)
+// would otherwise take the whole app down.
 process.on('unhandledRejection', (err) => {
-  console.log('UNHANDLED REJECTION! Shutting down...');
+  console.error('UNHANDLED REJECTION!', err?.name, err?.message);
-  console.log(err.name, err.message);
+  console.error(err?.stack || err);
-  process.exit(1);
 });
 
 module.exports = { app, prisma };