Initial commit: step2urdf tool with handtuned JSON import.

Includes FastAPI backend, vendored step2urdf frontend, and A7 handtuned arm JSON for URDF generation.

frontend/types/env.d.ts

@@ -0,0 +1,7 @@
+/// <reference types="vite/client" />
+
+declare module '*.vue' {
+    import type { DefineComponent } from 'vue'
+    const component: DefineComponent<{}, {}, any>
+    export default component
+}