- Add ModalProvider context and useConfirm hook (confirm-modal.tsx)
- Support danger/warning/info variants with icons and colors
- Animated backdrop and dialog with CSS keyframes
- Accessible: aria-modal, role=dialog, ESC to close, auto-focus
- Replace all 6 native confirm() calls across dashboard pages
- Integrate ModalProvider in app providers
- Backend: billing module with ServicePlan, PricingRule, Wallet, WalletTransaction entities
- Admin can CRUD service plans with hourly/monthly/yearly billing cycles
- Each plan has flexible pricing rules (base_fee, cpu, memory, storage, db addon)
- Wallet system: auto-created per user, charge, deduct, refund, transaction history
- Cost calculation endpoint: cross-cycle conversion (hourly*720=monthly, monthly*12=yearly)
- Frontend: admin billing management page (/dashboard/admin/billing)
- Frontend: user wallet page with balance, quick-charge, transaction history
- Deploy page: cost breakdown shown in Review step (hourly/monthly/yearly)
- Navigation: Wallet link for users, Billing Plans link for admins