feat: add phone field to User model and update authentication flow

- Added phone field to User model in Prisma schema and generated types.
- Updated backend authentication to include phone as an additional field.
- Implemented phone input in the signup form with validation.
- Created a new SignupPage component for user registration.
- Updated routing to include signup path and redirect authenticated users.
- Modified login page to reference Playzer and added link to signup.

apps/backend/prisma/auth.prisma

@@ -4,6 +4,7 @@ model User {
     email         String
     emailVerified Boolean   @default(false)
     image         String?
+    phone         String?
     createdAt     DateTime  @default(now())
     updatedAt     DateTime  @updatedAt
     sessions      Session[]