feat(users): add block/unblock and delete from admin panel

- Migration 0004: adds is_active column to users table
- Backend: DELETE /users/:id endpoint + is_active field in UpdateUserDto
- Admin UI: block/unblock toggle and delete with confirmation on user detail
- Users list: shows "Bloqueado" badge for inactive users

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

backend/prisma/schema.prisma

@@ -227,6 +227,7 @@ model users {
   fcm_token                               String?
   is_phone_verified                       Boolean?       @default(false)
   is_email_verified                       Boolean?       @default(false)
+  is_active                               Boolean        @default(true)
   created_at                              DateTime       @default(now()) @db.Timestamptz(6)
   updated_at                              DateTime       @default(now()) @db.Timestamptz(6)
   chats_chats_professional_idTousers      chats[]        @relation("chats_professional_idTousers")