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-router/README.md

@@ -0,0 +1,16 @@
+# React Router
+
+The `react-router` package is the heart of [React Router](https://github.com/remix-run/react-router) and provides all
+the core functionality for both
+[`react-router-dom`](https://github.com/remix-run/react-router/tree/main/packages/react-router-dom)
+and
+[`react-router-native`](https://github.com/remix-run/react-router/tree/main/packages/react-router-native).
+
+If you're using React Router, you should never `import` anything directly from
+the `react-router` package, but you should have everything you need in either
+`react-router-dom` or `react-router-native`. Both of those packages re-export
+everything from `react-router`.
+
+If you'd like to extend React Router and you know what you're doing, you should
+add `react-router` **as a peer dependency, not a regular dependency** in your
+package.