Update user profile to allow optional email and correct name updates

Fix bug where email was mandatory on user profile updates and ensure last name field updates correctly.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: a8a78c07-e900-425c-a577-5b4c5894379d
Replit-Commit-Checkpoint-Type: full_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/1957c339-2757-4d1f-8e92-e9f71a1ce58e/a8a78c07-e900-425c-a577-5b4c5894379d/vetH0Gp

server/routes.ts

@@ -937,7 +937,7 @@ export async function registerRoutes(app: Express): Promise<Server> {
         role: z.enum(['admin', 'manager', 'employee']).optional(),
         firstName: z.string().optional(),
         lastName: z.string().optional(),
-        email: z.string().email().optional(),
+        email: z.union([z.string().email(), z.literal("")]).optional(),
         password: z.string().optional(),
       });