Initial commit: Unity Needle AR Menu project with MenuScene and SampleScene web apps

Add root .gitignore for Unity Library/Temp/Logs, IDE folders, and node_modules.
Include Assets, Needle TypeScript (MenuController, asset picker, WebXR), and project configuration.

Made-with: Cursor

Needle/MenuScene/src/enableXR.ts

@@ -0,0 +1,20 @@
+import { onStart, WebXR } from "@needle-tools/engine";
+
+/**
+ * WebXR (AR/VR) — https://engine.needle.tools/docs/how-to-guides/xr/
+ *
+ * Unity editor (parity with Gitea): use XR Flag on content so meshes stay visible in AR; author dish
+ * scale for real-world size. If the scene already has WebXR from export, we only tune placement.
+ */
+onStart((context) => {
+  let webxr = context.scene.getComponentInChildren(WebXR);
+  if (!webxr) {
+    webxr = context.scene.addComponent(WebXR);
+    webxr.createARButton = true;
+    webxr.createVRButton = true;
+  }
+
+  webxr.autoPlace = true;
+  webxr.autoCenter = true;
+  webxr.arScale = 1;
+});