refactor(examples): hide workout dispatch details

Keep the workout binary to page/runtime/interaction plumbing by moving generated handle dispatch behind an app-owned interactions function, while preserving typed form adapters and full verification.

req: codegen/002

req: examples/001

examples/workout/src/main.rs

@@ -39,7 +39,7 @@ async fn interact(
     State(state): State<AppState>,
     request: InteractionRequest,
 ) -> Result<EffectResponse, impl IntoResponse> {
-    request.dispatch_async(workout_app::registry(state)).await
+    request.dispatch(workout_app::interactions(state))
 }
 
 async fn workout_css() -> impl IntoResponse {