feat(admin): add admin panel with user management, daily puzzle CRUD, and activity graph

- Add admin page at /admin (restricted to ADMIN_EMAIL via proxy)
- Implement user ban/unban and deletion
- Add daily puzzle creation, modification, deletion
- Include 14-day activity chart with hover details
- Add User.banned field to schema and migrate database
- Block banned users from logging in
- Add ADMIN_EMAIL to .env.local configuration
- Update Prisma client after schema changes

lib/generated/prisma/models/Game.ts

@@ -535,10 +535,6 @@ export type FloatFieldUpdateOperationsInput = {
   divide?: number
 }
 
-export type BoolFieldUpdateOperationsInput = {
-  set?: boolean
-}
-
 export type GameCreateWithoutUserInput = {
   id?: string
   mode: string