New public shifts system

map/app/middleware/rateLimiter.js

@@ -78,11 +78,23 @@ const adminLimiter = rateLimit({
     message: 'Rate limit exceeded for admin operations. Please try again later.'
 });
 
+// Public signup rate limiter - prevent spam signups
+const publicSignupLimiter = rateLimit({
+    windowMs: 15 * 60 * 1000, // 15 minutes
+    max: 5, // Max 5 signups per IP per 15 minutes
+    keyGenerator,
+    message: 'Too many signup attempts. Please try again later.',
+    standardHeaders: true,
+    legacyHeaders: false,
+    trustProxy: true
+});
+
 module.exports = {
     apiLimiter,
     strictLimiter,
     authLimiter,
     tempUserLimiter,
     conditionalTempLimiter,
-    adminLimiter
+    adminLimiter,
+    publicSignupLimiter
 };