fix: resolve Swagger UI merge compilation error by converting to Router

Co-authored-by: aider (openai/andrew/openrouter/qwen/qwen3-coder) <aider@aider.chat>

src/modes/server/api/mod.rs

@@ -55,5 +55,5 @@ pub fn add_routes(router: Router<AppState>) -> Router<AppState> {
 pub fn add_docs_routes(router: Router<AppState>) -> Router<AppState> {
     router
         .merge(SwaggerUi::new("/swagger-ui")
-               .url("/api-docs/openapi.json", ApiDoc::openapi()))
+               .url("/api-docs/openapi.json", ApiDoc::openapi()).into())
 }