Web dashboard: dashboard module scaffold for parallel steps

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NHyYupFdBiR4VfoUM7NjSM

src/web/dashboard/users.rs

@@ -0,0 +1,10 @@
+//! Dashboard: users pages. Filled in by web dashboard plan step 7.
+
+use axum::Router;
+
+use crate::server::AppState;
+
+/// Routes contributed by this page group (merged by `dashboard::router`).
+pub fn routes() -> Router<AppState> {
+    Router::new()
+}