fix(sim-auth): always send signup name and validate credentials

Backend/public/mobile-sim.js

@@ -147,11 +147,17 @@
         });
       };
 
-      const getAuthPayload = () => ({
-        name: $('authName').value.trim() || undefined,
-        email: $('authEmail').value.trim(),
+      const getAuthPayload = () => {
+        const email = $('authEmail').value.trim();
+        const explicitName = $('authName').value.trim();
+        const inferredName = email.includes('@') ? email.split('@')[0] : email;
+
+        return {
+          name: explicitName || inferredName || 'SecureCam User',
+          email,
           password: $('authPassword').value,
-      });
+        };
+      };
 
       const connectSocket = () => {
         if (!state.deviceToken) throw new Error('Register device first');
@@ -227,9 +233,18 @@
 
       $('signUpBtn').addEventListener('click', async () => {
         try {
+          const authPayload = getAuthPayload();
+          if (!authPayload.email || !authPayload.password) {
+            throw new Error('Email and password are required');
+          }
+
+          if (authPayload.password.length < 8) {
+            throw new Error('Password must be at least 8 characters');
+          }
+
           const payload = await authFetch('/api/auth/sign-up/email', {
             method: 'POST',
-            body: JSON.stringify(getAuthPayload()),
+            body: JSON.stringify(authPayload),
           });
           log('sign up', payload);
           $('sessionBtn').click();
@@ -241,6 +256,10 @@
       $('signInBtn').addEventListener('click', async () => {
         try {
           const authPayload = getAuthPayload();
+          if (!authPayload.email || !authPayload.password) {
+            throw new Error('Email and password are required');
+          }
+
           const payload = await authFetch('/api/auth/sign-in/email', {
             method: 'POST',
             body: JSON.stringify({ email: authPayload.email, password: authPayload.password }),