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>

server/node_modules/inherits/README.md

@@ -0,0 +1,42 @@
+Browser-friendly inheritance fully compatible with standard node.js
+[inherits](http://nodejs.org/api/util.html#util_util_inherits_constructor_superconstructor).
+
+This package exports standard `inherits` from node.js `util` module in
+node environment, but also provides alternative browser-friendly
+implementation through [browser
+field](https://gist.github.com/shtylman/4339901). Alternative
+implementation is a literal copy of standard one located in standalone
+module to avoid requiring of `util`. It also has a shim for old
+browsers with no `Object.create` support.
+
+While keeping you sure you are using standard `inherits`
+implementation in node.js environment, it allows bundlers such as
+[browserify](https://github.com/substack/node-browserify) to not
+include full `util` package to your client code if all you need is
+just `inherits` function. It worth, because browser shim for `util`
+package is large and `inherits` is often the single function you need
+from it.
+
+It's recommended to use this package instead of
+`require('util').inherits` for any code that has chances to be used
+not only in node.js but in browser too.
+
+## usage
+
+```js
+var inherits = require('inherits');
+// then use exactly as the standard one
+```
+
+## note on version ~1.0
+
+Version ~1.0 had completely different motivation and is not compatible
+neither with 2.0 nor with standard node.js `inherits`.
+
+If you are using version ~1.0 and planning to switch to ~2.0, be
+careful:
+
+* new version uses `super_` instead of `super` for referencing
+  superclass
+* new version overwrites current prototype while old one preserves any
+  existing fields on it