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/jsonwebtoken/lib/timespan.js

@@ -0,0 +1,18 @@
+var ms = require('ms');
+
+module.exports = function (time, iat) {
+  var timestamp = iat || Math.floor(Date.now() / 1000);
+
+  if (typeof time === 'string') {
+    var milliseconds = ms(time);
+    if (typeof milliseconds === 'undefined') {
+      return;
+    }
+    return Math.floor(timestamp + milliseconds / 1000);
+  } else if (typeof time === 'number') {
+    return timestamp + time;
+  } else {
+    return;
+  }
+
+};