useAssetViewer Hook (#182)

* Enhance Splat Viewer by adding useAssetViewer hook and updating documentation

- Imported and exported the useAssetViewer hook from the splat-viewer-context to provide imperative access to the asset viewer.
- Updated documentation to include details about the useAssetViewer hook, explaining its purpose and usage for triggering downloads, toggling fullscreen mode, and accessing loading progress.

* Add changeset for useAssetViewer hook in Splat Viewer

- Introduced the `useAssetViewer` hook to enhance the Splat Viewer functionality.
- Updated documentation to reflect the new hook and its usage.

* Update packages/docs/content/blocks/splat-viewer.mdx

Co-authored-by: Copilot <[email protected]>

---------

Co-authored-by: Copilot <[email protected]>

Author: marklundin

.changeset/orange-bikes-give.md

@@ -0,0 +1,6 @@
+---
+"@playcanvas/blocks": minor
+"docs": patch
+---
+
+We now expose the `useAssetViewer` hook which provides API and context to the Splat Viewer

packages/blocks/src/index.ts

@@ -1,3 +1,4 @@
 // Splat Viewer
 import * as Viewer from "./splat-viewer/index.ts"
-export { Viewer };
+import { useAssetViewer } from "./splat-viewer/splat-viewer-context.ts";
+export { Viewer, useAssetViewer };

packages/docs/content/blocks/splat-viewer.mdx

@@ -168,6 +168,18 @@ A responsive and composable component for displaying **Gaussian splats**.
   `}
 />
 
+#### useAssetViewer
+
+A hook that provides the context for the asset viewer. This is handy if you need an imperative handle for the viewer. Use this if you need to trigger a download, or toggle the fullscreen mode, or access the loading progress.
+
+<TSDoc
+  code={`
+    import { useAssetViewer } from '@playcanvas/blocks';
+    type $ = ReturnType<typeof useAssetViewer>;
+    export default $;
+  `}
+/>
+
 #### Controls
 
 A simple container for UI controls that creates a sensible layout and optionally auto hides when the user is interacting.