feat: add country and city fields to user profile

- Add country and city fields to User model
- Create database migration for location fields
- Add validation for country and city (max 100 characters)
- Create countries.js with complete list of 195 countries
- Add country dropdown select and city text input to profile page
- Include country and city in GET /api/users/me response
- Update profile form to support location data

Users can now select their country from a dropdown list of all
countries and enter their city name.

backend/src/controllers/user.js

@@ -10,7 +10,7 @@ const { sanitizeForEmail } = require('../utils/sanitize');
 async function updateProfile(req, res, next) {
   try {
     const userId = req.user.id;
-    const { firstName, lastName, email, wsdcId, youtubeUrl, instagramUrl, facebookUrl, tiktokUrl } = req.body;
+    const { firstName, lastName, email, wsdcId, youtubeUrl, instagramUrl, facebookUrl, tiktokUrl, country, city } = req.body;
 
     // Build update data
     const updateData = {};
@@ -21,6 +21,8 @@ async function updateProfile(req, res, next) {
     if (instagramUrl !== undefined) updateData.instagramUrl = instagramUrl || null;
     if (facebookUrl !== undefined) updateData.facebookUrl = facebookUrl || null;
     if (tiktokUrl !== undefined) updateData.tiktokUrl = tiktokUrl || null;
+    if (country !== undefined) updateData.country = country || null;
+    if (city !== undefined) updateData.city = city || null;
 
     // Check if email is being changed
     const currentUser = await prisma.user.findUnique({