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/kanban/src/lib.rs

@@ -5,9 +5,9 @@ pub mod ui {}
 mod tests {
     use super::ui::{board, board_card};
     use hemplate::Hemplate;
-    use scraper::{Html, Selector};
     use hemx::IntoEffect;
     use hemx_test::inspect;
+    use scraper::{Html, Selector};
 
     #[derive(Hemplate)]
     #[hemplate = "partials"]

examples/kanban/src/main.rs

@@ -6,8 +6,8 @@ use futures_util::{stream, StreamExt};
 use hemplate::Hemplate;
 use hemx::{Html, IntoEffect};
 use hemx_axum::{
-    interactions, runtime_js, sse, DispatchRegistry, DispatchRejection, EffectResponse,
-    InteractionRequest, PageRequest,
+    interactions, runtime_js, runtime_js_path, sse, DispatchRegistry, DispatchRejection,
+    EffectResponse, InteractionRequest, PageRequest,
 };
 use hemx_kanban_example::ui::board::{self as board};
 use hemx_kanban_example::ui::board_card as card_board;
@@ -40,6 +40,7 @@ struct Card {
 
 #[derive(Hemplate)]
 struct AppShell {
+    runtime_src: &'static str,
     body: Html,
 }
 
@@ -118,7 +119,7 @@ async fn main() {
     let app = Router::new()
         .route("/", get(home).post(interact))
         .route("/events", get(events))
-        .route("/hemx.js", get(runtime))
+        .route(runtime_js_path(), get(runtime))
         .with_state(state);
 
     let addr = SocketAddr::from(([127, 0, 0, 1], 3001));
@@ -288,7 +289,10 @@ fn page_html(board: &BoardState) -> Html {
 
 fn shell(body: Html) -> Html {
     // req: html_safety/001 req: html_safety/002 req: axum_integration/001
-    hemx::page(&AppShell { body })
+    hemx::page(&AppShell {
+        runtime_src: runtime_js_path(),
+        body,
+    })
 }
 
 fn render_options() -> Html {

examples/kanban/templates/app_shell.heml

@@ -4,7 +4,7 @@
   <meta charset="utf-8">
   <meta name="viewport" content="width=device-width, initial-scale=1">
   <title>hemx Kanban</title>
-  <script src="/hemx.js" defer></script>
+  <script +src="self.runtime_src" defer></script>
   <style>
     body { font-family: system-ui, sans-serif; margin: 2rem; }
     form { display: flex; gap: .5rem; flex-wrap: wrap; margin: 1rem 0; }