feat: port StationBuilder Vue app from ant-design-vue to Element Plus

feat: port StationBuilder Vue app from ant-design-vue to Element Plus

- Replace antd runtime theme injection with static brand-token CSS bridge
  (brand-tokens.css defines all --ant-* vars so 2261 legacy custom-CSS refs
  survive, plus --el-* brand overrides: primary #008cd6, radius 4px, etc.)
- Rewrite Ui* wrapper layer (UiTable/UiButton/UiInput/UiSelect/UiActions/
  UiTabbedRegion/UiOverlay) to Element Plus; App.vue uses ElConfigProvider
- Replace antd QRCode with local QrCode.vue (qrcode npm package)
- Rename antd icons to Element Plus equivalents; fix invalid exports
  (Apartment->OfficeBuilding, Copy->CopyDocument/DocumentCopy)
- Remove dead tailwind import; add less devDependency for .less build