feat: launch 3d architecture documentation portal

docs/user-tutorial/start-here.md

@@ -0,0 +1,17 @@
+---
+title: "Start Here"
+description: "Open the first architecture model and establish the navigation path."
+slug: /
+---
+
+# Start with the browser POC
+
+The first project deliverable is one architecture model rendered in a navigable 3D scene. Use this path to enter the model, orient the camera, and select an architecture element.
+
+## Outcome
+
+You can identify the model boundary and move between its major elements.
+
+## Next step
+
+Continue to [Navigate the Model](./navigate-the-model.md).