Multi-tenant resource isolation #17
Description
Description\nImplement proper multi-tenant architecture with resource isolation.\n\nTasks\n- [ ] Tenant identification and auth\n- [ ] Resource quotas and limits\n- [ ] Isolated KV namespaces\n- [ ] Separate D1 databases per tenant\n- [ ] Billing and usage tracking\n\nArchitecture\n- Durable Objects for tenant state\n- KV for tenant config\n- D1 for tenant data\n