feat(product-center): implement full product center with NestJS backend, Vue3 admin, and Nuxt4 website page

- NestJS backend: Prisma + PostgreSQL, JWT auth, CRUD for goods/categories/countries/tags/positions, SDS sync with cron, public API, Swagger docs
- Vue3 Admin: Element Plus, goods/categories/countries/tags/positions/sync management pages, batch operations, login with JWT
- Nuxt4 Website: product-center page with sidebar navigation, country filter, search, product grid, pagination, skeleton loading
- Nitro proxy routes for backend API
- 54 backend tests passing
- Updated docs and README

inkreach-official-admin/.gitignore

@@ -0,0 +1,24 @@
+# Logs
+logs
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+lerna-debug.log*
+
+node_modules
+dist
+dist-ssr
+*.local
+
+# Editor directories and files
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+*.suo
+*.ntvs*
+*.njsproj
+*.sln
+*.sw?