feat(axum): expose hashed runtime asset path

Generate a SHA-256 content hash for the embedded hemx runtime, expose the hashed path from hemx-axum, serve immutable runtime headers, and update examples to load the hemx-owned path instead of fixed /hemx.js URLs.

req: axum_integration/005

examples/saas/src/main.rs

@@ -5,7 +5,7 @@ use axum::routing::get;
 use axum::Router;
 use futures_util::stream;
 use hemx::IntoEffect;
-use hemx_axum::{runtime_js, sse, EffectResponse, InteractionRequest};
+use hemx_axum::{runtime_js, runtime_js_path, sse, EffectResponse, InteractionRequest};
 use hemx_saas_example::{home_page, live_status, registry, settings_page, ui, AppContext};
 use std::collections::BTreeMap;
 use std::convert::Infallible;
@@ -26,7 +26,7 @@ fn app(ctx: AppContext) -> Router {
         .route("/", get(home).post(interact))
         .route("/settings", get(settings))
         .route("/events", get(events))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .route("/app.css", get(css))
         .route("/metrics.js", get(metrics_js))
         .with_state(ctx)