docs: README and third-party notices for the React app

- README: setup with the HMDesign submodule/workspace, scripts,
  source layout (engine copied as is vs. new React components).
- THIRD-PARTY-NOTICES (root + served /licenses copy): acadrust MPL-2.0
  section unchanged; intro points at this app's dist/ and the in-app
  entry points; adds the UI runtime that @hm-design/ui brings in
  (React, Radix UI, lucide-react, class-variance-authority, shadcn CSS,
  Noto Sans KR) and HMDesign itself (#1).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

public/licenses/THIRD-PARTY-NOTICES.md

@@ -1,9 +1,10 @@
 # Third-party notices
 
-This viewer bundles third-party code. The notices below apply to the source
-tree **and** to the built site (`dist2/`, deployed at
-`https://dwg-dxf-viewer-sample.pages.dev/`), because the build embeds the
-components listed here.
+This viewer (dwg-dxf-viewer-hm — the React/HMDesign rebuild of
+dwg-dxf-viewer-sample) bundles third-party code. The notices below apply to the
+source tree **and** to the built site (`dist/`), because the build embeds the
+components listed here. In the app they are reachable from the GNB info button
+and the status-bar link "오픈소스 고지".
 
 Served copies of the license texts live under
 [`public/licenses/`](./public/licenses/) → `/licenses/…` on the deployed site.
@@ -67,4 +68,11 @@ MPL-covered files above keep their license — which they do.
 | dxf-parser | MIT |
 | opentype.js | MIT |
 | NanumGothic (`public/fonts/`) | SIL Open Font License 1.1 |
-| Viewer2D / sample glue | MIT |
+| Viewer2D / sample glue / React app code | MIT |
+| React, React DOM, scheduler | MIT |
+| Radix UI (`radix-ui`), sonner, cmdk, vaul, embla-carousel, react-day-picker, react-resizable-panels, @tanstack/react-table, cn, tw-animate-css (via `@hm-design/ui`) | MIT |
+| lucide-react | ISC |
+| class-variance-authority | Apache-2.0 |
+| shadcn/ui CSS vendored by `@hm-design/ui` (`dist/vendor/shadcn-tailwind.css`) | MIT |
+| Noto Sans KR (HMDesign theme font, `dist/fonts/`) | SIL Open Font License 1.1 |
+| HMDesign (`@hm-design/ui`, git submodule `vendor/HMDesign`) | Internal design system; its package declares no license (see the submodule) |