hive-agent: replace json! with typed structs in web_ui handlers

hive-agent/src/web_ui/actions.rs

@@ -7,7 +7,7 @@ use axum::{
     http::StatusCode,
     response::{IntoResponse, Response},
 };
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 
 use super::{AppState, SigintOutcome, error_response};
 
@@ -202,5 +202,10 @@ pub(super) async fn post_mark_todos_done(Form(form): Form<MarkTodosDoneForm>) ->
             acked += count;
         }
     }
-    axum::Json(serde_json::json!({ "acked": acked })).into_response()
+    axum::Json(MarkTodosDoneBody { acked }).into_response()
+}
+
+#[derive(Serialize)]
+struct MarkTodosDoneBody {
+    acked: u64,
 }