Add Milestones 1 & 2: full-stack POS foundation with admin UI

- Node/Express/TypeScript API under /api/v1 with JWT auth (login, refresh, logout, /me)
- Prisma schema: vendors, users, roles, products, categories, taxes, transactions
- SQLite for local dev; Postgres via docker-compose for production
- Full CRUD routes for vendors, users, categories, taxes, products with Zod validation and RBAC
- Paginated list endpoints scoped per vendor; refresh token rotation
- React/TypeScript admin SPA (Vite): login, protected routing, sidebar layout
- Pages: Dashboard, Catalog (tabbed Products/Categories/Taxes), Users, Vendor Settings
- Shared UI: Table, Modal, FormField, Btn, PageHeader components
- Multi-stage Dockerfile; docker-compose with Postgres healthcheck
- Seed script with demo vendor and owner account
- INSTRUCTIONS.md, ROADMAP.md, .claude/launch.json for dev server config

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

client/node_modules/react-refresh/README.md

@@ -0,0 +1,5 @@
+# react-refresh
+
+This package implements the wiring necessary to integrate Fast Refresh into bundlers. Fast Refresh is a feature that lets you edit React components in a running application without losing their state. It is similar to an old feature known as "hot reloading", but Fast Refresh is more reliable and officially supported by React.
+
+This package is primarily aimed at developers of bundler plugins. If you’re working on one, here is a [rough guide](https://github.com/facebook/react/issues/16604#issuecomment-528663101) for Fast Refresh integration using this package.