Feat: clean the codebase as much as possible

src/input/mod.rs

@@ -209,7 +209,7 @@ fn load_project_samples(ctx: &mut InputContext) {
             std::thread::Builder::new()
                 .name("sample-preload".into())
                 .spawn(move || {
-                    crate::init::preload_sample_heads(all_preload_entries, sr, &registry);
+                    crate::engine::preload_sample_heads(all_preload_entries, sr, &registry);
                 })
                 .expect("failed to spawn preload thread");
         }