refactor: centralize editor interaction state

Move timeline and preview gestures into dedicated controllers so hooks stay thin around editor state and DOM events.

This also routes drag and playback synchronization through manager APIs and reuses persistent wasm surfaces so scrubbing, seeking, and preview rendering stay in sync.

Made-with: Cursor

rust/crates/compositor/src/compositor.rs

@@ -348,7 +348,6 @@ impl Compositor {
     ) -> Result<(), CompositorError> {
         let frame = options.frame;
         self.texture_pool.recycle_frame();
-        context.configure_surface(options.surface, frame.width, frame.height)?;
         let surface_texture = context.acquire_surface_texture(options.surface)?;
         let surface_view = surface_texture
             .texture