chore: refactor user profile repository for UUID (refs #214)

Updated user-profile.repository.ts to use UUID instead of auth0_sub:
- Added getById(id) method for UUID-based lookups
- Changed all methods (except getByAuth0Sub, getOrCreate) to accept userId (UUID) instead of auth0Sub
- Updated SQL WHERE clauses from auth0_sub to id for UUID-based queries
- Fixed cross-table joins in listAllUsers and getUserWithAdminStatus to use user_profile_id
- Updated hardDeleteUser to use UUID for all DELETE statements
- Updated auth.plugin.ts to call updateEmail and updateEmailVerified with userId (UUID)

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

backend/src/core/plugins/auth.plugin.ts

@@ -166,9 +166,9 @@ const authPlugin: FastifyPluginAsync = async (fastify) => {
 
         // If profile has placeholder email but we now have real email, update it
         if (profile.email.includes('@unknown.local') && email && !email.includes('@unknown.local')) {
-          await profileRepo.updateEmail(auth0Sub, email);
+          await profileRepo.updateEmail(userId, email);
           logger.info('Updated profile with correct email from Auth0', {
-            userId: auth0Sub.substring(0, 8) + '...',
+            userId: userId.substring(0, 8) + '...',
           });
         }
 
@@ -184,16 +184,16 @@ const authPlugin: FastifyPluginAsync = async (fastify) => {
           try {
             const isVerifiedInAuth0 = await auth0ManagementClient.checkEmailVerified(auth0Sub);
             if (isVerifiedInAuth0 && !profile.emailVerified) {
-              await profileRepo.updateEmailVerified(auth0Sub, true);
+              await profileRepo.updateEmailVerified(userId, true);
               emailVerified = true;
               logger.info('Synced email verification status from Auth0', {
-                userId: auth0Sub.substring(0, 8) + '...',
+                userId: userId.substring(0, 8) + '...',
               });
             }
           } catch (syncError) {
             // Don't fail auth if sync fails, just log
             logger.warn('Failed to sync email verification status', {
-              userId: auth0Sub.substring(0, 8) + '...',
+              userId: userId.substring(0, 8) + '...',
               error: syncError instanceof Error ? syncError.message : 'Unknown error',
             });
           }