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/ee-first/index.js

@@ -0,0 +1,95 @@
+/*!
+ * ee-first
+ * Copyright(c) 2014 Jonathan Ong
+ * MIT Licensed
+ */
+
+'use strict'
+
+/**
+ * Module exports.
+ * @public
+ */
+
+module.exports = first
+
+/**
+ * Get the first event in a set of event emitters and event pairs.
+ *
+ * @param {array} stuff
+ * @param {function} done
+ * @public
+ */
+
+function first(stuff, done) {
+  if (!Array.isArray(stuff))
+    throw new TypeError('arg must be an array of [ee, events...] arrays')
+
+  var cleanups = []
+
+  for (var i = 0; i < stuff.length; i++) {
+    var arr = stuff[i]
+
+    if (!Array.isArray(arr) || arr.length < 2)
+      throw new TypeError('each array member must be [ee, events...]')
+
+    var ee = arr[0]
+
+    for (var j = 1; j < arr.length; j++) {
+      var event = arr[j]
+      var fn = listener(event, callback)
+
+      // listen to the event
+      ee.on(event, fn)
+      // push this listener to the list of cleanups
+      cleanups.push({
+        ee: ee,
+        event: event,
+        fn: fn,
+      })
+    }
+  }
+
+  function callback() {
+    cleanup()
+    done.apply(null, arguments)
+  }
+
+  function cleanup() {
+    var x
+    for (var i = 0; i < cleanups.length; i++) {
+      x = cleanups[i]
+      x.ee.removeListener(x.event, x.fn)
+    }
+  }
+
+  function thunk(fn) {
+    done = fn
+  }
+
+  thunk.cancel = cleanup
+
+  return thunk
+}
+
+/**
+ * Create the event listener.
+ * @private
+ */
+
+function listener(event, done) {
+  return function onevent(arg1) {
+    var args = new Array(arguments.length)
+    var ee = this
+    var err = event === 'error'
+      ? arg1
+      : null
+
+    // copy args to prevent arguments escaping scope
+    for (var i = 0; i < args.length; i++) {
+      args[i] = arguments[i]
+    }
+
+    done(err, ee, event, args)
+  }
+}