simplify: unify route structs, fix prefix collision, lint fixes

- Unify RouteConfig/RouteEntry/RouteResponse into single RouteEntry
- Fix prefix collision: /api no longer matches /apiary (segment boundary check)
- Add path traversal rejection in route API
- Extract MdnsAnnouncement struct (clippy type_complexity)
- cargo fmt

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/api.rs

@@ -761,7 +761,10 @@ async fn add_route(
     if store.add_route(&name, req.path, req.port, req.strip) {
         Ok(StatusCode::CREATED)
     } else {
-        Err((StatusCode::NOT_FOUND, format!("service '{}' not found", name)))
+        Err((
+            StatusCode::NOT_FOUND,
+            format!("service '{}' not found", name),
+        ))
     }
 }