feat: language selector on user creation, pass to welcome email

Adds preferred_language field to Users, language picker (EN/AR) in
create/edit user form, persists to NocoDB, and passes it to the
welcome notification so new users receive emails in their language.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/server.js

@@ -947,7 +947,7 @@ app.get('/api/users/team', requireAuth, async (req, res) => {
 });
 
 app.post('/api/users/team', requireAuth, requireRole('superadmin', 'manager'), async (req, res) => {
-  const { name, email, password, team_role, brands, phone, role, role_id, avatar } = req.body;
+  const { name, email, password, team_role, brands, phone, role, role_id, avatar, preferred_language } = req.body;
   if (!name) return res.status(400).json({ error: 'Name is required' });
   if (!email) return res.status(400).json({ error: 'Email is required' });
 
@@ -972,11 +972,12 @@ app.post('/api/users/team', requireAuth, requireRole('superadmin', 'manager'), a
       password_hash: passwordHash,
       role_id: role_id || null,
       avatar: avatar || null,
+      preferred_language: preferred_language || 'en',
     });
 
     const user = await nocodb.get('Users', created.Id);
     res.status(201).json(stripSensitiveFields({ ...user, id: user.Id, _id: user.Id }));
-    notify.notifyUserInvited({ email, name, password: defaultPassword, inviterName: req.session.userName });
+    notify.notifyUserInvited({ email, name, password: defaultPassword, inviterName: req.session.userName, lang: preferred_language || 'en' });
   } catch (err) {
     console.error('Create team member error:', err);
     res.status(500).json({ error: 'Failed to create team member' });
@@ -989,7 +990,7 @@ app.patch('/api/users/team/:id', requireAuth, requireRole('superadmin', 'manager
     if (!existing) return res.status(404).json({ error: 'User not found' });
 
     const data = {};
-    for (const f of ['name', 'email', 'team_role', 'phone', 'avatar']) {
+    for (const f of ['name', 'email', 'team_role', 'phone', 'avatar', 'preferred_language']) {
       if (req.body[f] !== undefined) data[f] = req.body[f];
     }
     if (req.body.brands !== undefined) data.brands = JSON.stringify(req.body.brands);