feat: React19+HMDesign shell with ported DWG/DXF viewer engine

Scaffolds the new app (Vite+React19+Tailwind v4) on HMDesign via git
submodule + npm workspace, ports src/viewer2d/* and optionsStore.ts
unchanged, and rebuilds the vanilla UI (toolbar/layers/properties/
options panels, coord readout, license dialog, load progress) as HM
Design System components. Panel drag/collapse ported from
panelUtils.ts as a React hook; Measure UI intentionally left
unwired per original app parity.

Typecheck and dev-server module serving verified; in-browser
rendering not yet verified in this session (no browser tool
available) — needs manual check.

Refs #1

src/viewer2d/acadrust-dwg/acadrust_dwg_bg.wasm.d.ts

@@ -0,0 +1,11 @@
+/* tslint:disable */
+/* eslint-disable */
+export const memory: WebAssembly.Memory;
+export const parse_dwg: (a: number, b: number) => [number, number, number];
+export const parse_dwg_json: (a: number, b: number) => [number, number, number, number];
+export const __wbindgen_malloc: (a: number, b: number) => number;
+export const __wbindgen_realloc: (a: number, b: number, c: number, d: number) => number;
+export const __wbindgen_externrefs: WebAssembly.Table;
+export const __externref_table_dealloc: (a: number) => void;
+export const __wbindgen_free: (a: number, b: number, c: number) => void;
+export const __wbindgen_start: () => void;