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/src/types/index.ts

@@ -0,0 +1,33 @@
+import { Request } from "express";
+
+export interface AuthPayload {
+  userId: string;
+  vendorId: string;
+  roleId: string;
+  roleName: string;
+}
+
+export interface AuthenticatedRequest extends Request {
+  auth: AuthPayload;
+}
+
+export interface ApiError {
+  code: string;
+  message: string;
+  details?: unknown;
+}
+
+export interface PaginationQuery {
+  page?: number;
+  limit?: number;
+}
+
+export interface PaginatedResponse<T> {
+  data: T[];
+  pagination: {
+    page: number;
+    limit: number;
+    total: number;
+    totalPages: number;
+  };
+}