fix: profile page form pre-population and WSDC ID editing

- Add useEffect to pre-fill profile form with current user data
- Add WSDC ID field to profile edit form with numeric validation
- Update backend to accept wsdcId in profile updates with null handling
- Add wsdcId validation to updateProfileValidation middleware
- Include firstName, lastName, wsdcId in GET /api/users/me response

Fixes issue where profile inputs were empty on page load and allows
users to update their WSDC ID.

backend/src/controllers/user.js

@@ -10,12 +10,13 @@ const { sanitizeForEmail } = require('../utils/sanitize');
 async function updateProfile(req, res, next) {
   try {
     const userId = req.user.id;
-    const { firstName, lastName, email } = req.body;
+    const { firstName, lastName, email, wsdcId } = req.body;
 
     // Build update data
     const updateData = {};
     if (firstName !== undefined) updateData.firstName = firstName;
     if (lastName !== undefined) updateData.lastName = lastName;
+    if (wsdcId !== undefined) updateData.wsdcId = wsdcId || null; // Allow empty string to clear WSDC ID
 
     // Check if email is being changed
     const currentUser = await prisma.user.findUnique({