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/lib.rs

@@ -4,7 +4,8 @@ pub mod ui {}
 use hemplate::Hemplate;
 use hemx::{push, Html, IntoEffect};
 use hemx_axum::{
-    interactions, Form, HandlerErrorContext, HandlerFailure, IntoHandlerFailure, Registry, State,
+    interactions, runtime_js_path, Form, HandlerErrorContext, HandlerFailure, IntoHandlerFailure,
+    Registry, State,
 };
 use std::convert::Infallible;
 use std::fmt::Display;
@@ -248,12 +249,14 @@ impl SettingsPage {
 #[derive(Hemplate)]
 pub struct AppShell {
     title: &'static str,
+    runtime_src: &'static str,
     body: Html,
 }
 
 pub fn home_page(ctx: &AppContext) -> Html {
     hemx::page(&AppShell {
         title: "hemx SaaS tutorial",
+        runtime_src: runtime_js_path(),
         body: hemx::page(&Dashboard::from_context(ctx)),
     })
 }
@@ -261,6 +264,7 @@ pub fn home_page(ctx: &AppContext) -> Html {
 pub fn settings_page(ctx: &AppContext) -> Html {
     hemx::page(&AppShell {
         title: "hemx SaaS tutorial settings",
+        runtime_src: runtime_js_path(),
         body: hemx::page(&Dashboard::settings(ctx)),
     })
 }