feat: add employee email verification on signup

- Signup sends verification email instead of auto-login; login blocks unverified emails
- New endpoints: POST /verify-email and POST /resend-verification
- New verify-email page in dashboard with token-based email confirmation
- DB migration adds emailVerified and emailVerificationToken fields to Employee
- Update sign-in/sign-up/reset-password flows to handle verification states
- Minor UI polish across dashboard and marketplace components
- Refactor marketplace-homepage types

packages/database/prisma/schema.prisma

@@ -1001,6 +1001,8 @@ model Employee {
   passwordHash           String?
   passwordResetToken     String?      @unique
   passwordResetExpiresAt DateTime?
+  emailVerified          DateTime?
+  emailVerificationToken String?      @unique
   role                   EmployeeRole @default(AGENT)
   preferredLanguage      String       @default("en")
   isActive               Boolean      @default(true)