Add async task support to VX DOM and host runtime (#676)

## Summary
- Add async task plumbing across compiler, JS host, and VX DOM runtime
- Update web SSR/bootstrap and browser/runtime code paths to handle
async task commands
- Extend smoke, browser, and CLI tests plus the mini-wikipedia example
to cover the new flow

## Testing
- Added and updated unit, browser, and smoke coverage for async VX task
behavior
- Not run (not requested)

Author: drew-y

apps/cli/src/__tests__/bootstrap.test.ts

@@ -142,6 +142,10 @@ describe("runBootstrap", () => {
       const clientVoyd = await readFile(resolve(target, "src/client.voyd"), "utf8");
       expect(clientVoyd).toContain("pub fn app() -> Program<ClientArticle, Msg>");
       expect(clientVoyd).toContain("on_input={(event: InputEvent) -> Msg");
+      expect(clientVoyd).toContain("state_kind: String");
+      expect(clientVoyd).toContain("tasks::detach do:");
+      expect(clientVoyd).toContain("Cmd<Msg>::perform<i32>");
+      expect(clientVoyd).toContain("on_click={Msg::Save {}}");
       expect(clientVoyd).toContain("http_client::post");
 
       const css = await readFile(resolve(target, "src/style.css"), "utf8");
@@ -151,21 +155,21 @@ describe("runBootstrap", () => {
       const mainVoyd = await readFile(resolve(target, "src/main.voyd"), "utf8");
       expect(mainVoyd).toContain("pub fn main(): (server::HttpServer");
       expect(mainVoyd).toContain("tasks::TaskRuntime");
-      expect(mainVoyd).toContain("server::serve_each");
-      expect(mainVoyd).toContain("server::ServeTaskPolicy::sequential()");
+      expect(mainVoyd).toContain("serve(port: app_port(), host: app_host()");
       expect(mainVoyd).toContain("max_body_bytes: 65536");
-      expect(mainVoyd).toContain('adopt(serve_dir("./public".as_slice()))');
+      expect(mainVoyd).toContain('adopt(serve_dir("./public"))');
       expect(mainVoyd).not.toContain('"/api/articles"');
-      expect(mainVoyd).toContain('.get_context("/wiki".as_slice()');
-      expect(mainVoyd).toContain('.post_context("/wiki/:slug/body".as_slice()');
-      expect(mainVoyd).toContain('.post_context("/wiki/:slug".as_slice()');
+      expect(mainVoyd).toContain('get("/wiki") do(ctx: Context):');
+      expect(mainVoyd).toContain('post("/wiki/:slug/body") do(ctx: Context):');
+      expect(mainVoyd).toContain('post("/wiki/:slug") do(ctx: Context):');
       expect(mainVoyd).toContain("request_text_body(ctx)");
       expect(mainVoyd).toContain('form_article_body(request_text_body(ctx))');
       expect(mainVoyd).toContain('parse_query(input).get("body".as_slice())');
       expect(mainVoyd).toContain("write_file_string(article_path(slug), body)");
       expect(mainVoyd).toContain("fn is_slug_rune(rune: i32) -> bool");
       expect(mainVoyd).toContain("not is_slug_rune(rune)");
-      expect(mainVoyd).toContain("{article.status}");
+      expect(mainVoyd).toContain("state_kind: String");
+      expect(mainVoyd).toContain("{article.state_message}");
       expect(mainVoyd).not.toContain('>Saved</span>');
       expect(mainVoyd).toContain('href="/assets/client.css"');
       expect(mainVoyd).toContain("document<MsgPack, ClientArticle>");