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/nanoid/async/index.js

@@ -0,0 +1,35 @@
+import crypto from 'crypto'
+import { urlAlphabet } from '../url-alphabet/index.js'
+let random = bytes =>
+  new Promise((resolve, reject) => {
+    crypto.randomFill(Buffer.allocUnsafe(bytes), (err, buf) => {
+      if (err) {
+        reject(err)
+      } else {
+        resolve(buf)
+      }
+    })
+  })
+let customAlphabet = (alphabet, defaultSize = 21) => {
+  let mask = (2 << (31 - Math.clz32((alphabet.length - 1) | 1))) - 1
+  let step = Math.ceil((1.6 * mask * defaultSize) / alphabet.length)
+  let tick = (id, size = defaultSize) =>
+    random(step).then(bytes => {
+      let i = step
+      while (i--) {
+        id += alphabet[bytes[i] & mask] || ''
+        if (id.length >= size) return id
+      }
+      return tick(id, size)
+    })
+  return size => tick('', size)
+}
+let nanoid = (size = 21) =>
+  random((size |= 0)).then(bytes => {
+    let id = ''
+    while (size--) {
+      id += urlAlphabet[bytes[size] & 63]
+    }
+    return id
+  })
+export { nanoid, customAlphabet, random }