Scene storage backend integration (#51)

This PR adds Storyteller.ai API integration for saving and loading
Storyteller Studio scenes to/from the backend.

### Known issues
* The skybox is not currently stored in the serialized scene format

studio/src/main.rs

@@ -1,6 +1,6 @@
 use bevy::{app::Update, window::close_on_esc};
 use clap::Parser;
-use studio::{screenshot::ScreenShotPlugin, StudioMode, ViewportSize};
+use studio::{screenshot::ScreenShotPlugin, InitSeed, StudioMode, ViewportSize};
 
 #[derive(Parser)]
 #[command(name = "StorytellerStudio")]
@@ -16,13 +16,15 @@ struct StudioArgs {
 fn main() {
     let args = StudioArgs::parse();
 
-    let model_path = args.model.unwrap_or("Mannequin.gltf".to_string());
-    let skybox_path = args.skybox.unwrap_or("gum_trees_4k".to_string());
+    let object_id = args.model.unwrap_or("Mannequin.gltf".to_string());
+    let skybox_id = args.skybox.unwrap_or("gum_trees_4k".to_string());
 
     // Edit the arguments here to change the default startup scene or skybox
     let mut app = studio::start_internal(
-        model_path.as_str(),
-        skybox_path.as_str(),
+        InitSeed::FromLibrary {
+            object_id,
+            skybox_id,
+        },
         "", // ignored for non-WASM
         "Storyteller Studio",
         ViewportSize::default(),