feat(axum): add concise interaction request dispatch

Wrap extracted interaction forms in an InteractionRequest with a concise dispatch path, add a handlers() helper, and move canonical examples off direct HandlerRegistry/InteractionForm plumbing.

req: axum_integration/003

req: ceremony/001

req: dx/003

req: examples/003

examples/v0/src/main.rs

@@ -5,7 +5,9 @@ use axum::Router;
 use futures_util::{stream, StreamExt};
 use hemplate::Hemplate;
 use slhx::{push, IntoEffect, RenderSlotExt, SafeHtml};
-use slhx_axum::{runtime_js, sse, EffectResponse, HandlerRegistry, InteractionForm, PageRequest};
+use slhx_axum::{
+    handlers, runtime_js, sse, DispatchRegistry, EffectResponse, InteractionRequest, PageRequest,
+};
 use slhx_v0_examples::ui;
 use slhx_v0_examples::ui::{auth, counter, notifications, page_swap, todos, wizard};
 use slhx_v0_examples::ui::auth::{handles as auth_handles, slots as auth_slots};
@@ -96,9 +98,9 @@ async fn docs(request: PageRequest) -> impl IntoResponse {
 
 async fn interact(
     State(state): State<Arc<ExampleState>>,
-    form: InteractionForm,
+    request: InteractionRequest,
 ) -> Result<EffectResponse, impl IntoResponse> {
-    registry(state).dispatch(form)
+    request.dispatch(registry(state))
 }
 
 async fn runtime() -> impl IntoResponse {
@@ -121,8 +123,8 @@ async fn events(Query(params): Query<BTreeMap<String, String>>) -> impl IntoResp
     sse(batches)
 }
 
-fn registry(state: Arc<ExampleState>) -> HandlerRegistry {
-    HandlerRegistry::new(ui::BUILD_FINGERPRINT)
+fn registry(state: Arc<ExampleState>) -> impl DispatchRegistry {
+    handlers(ui::BUILD_FINGERPRINT)
         .register_handle(counter_handles::increment, {
             let state = state.clone();
             move |_| {