feat(admin): add comprehensive admin management system

- Add admin handlers and services for users, posts, comments, groups, and dashboard
- Implement role permission management with ability to view and update permissions
- Add database seeding for roles and Casbin permission policies
- Upgrade Casbin from v2 to v3 with GORM adapter for persistent policy storage
- Add admin-specific repository methods with filtering and pagination
- Register new admin API routes under /api/v1/admin/*

internal/wire/handler.go

@@ -22,6 +22,11 @@ var HandlerSet = wire.NewSet(
 	handler.NewStickerHandler,
 	handler.NewVoteHandler,
 	handler.NewRoleHandler,
+	handler.NewAdminUserHandler,
+	handler.NewAdminPostHandler,
+	handler.NewAdminCommentHandler,
+	handler.NewAdminGroupHandler,
+	handler.NewAdminDashboardHandler,
 
 	// 需要特殊处理的 Handler
 	ProvideUserHandler,