refactor: dump database to json

sdgb-api/src/lib.rs

@@ -6,3 +6,6 @@ mod error;
 pub use error::ApiError;
 
 pub use bincode;
+
+#[cfg(all(feature = "compio", feature = "tokio"))]
+compile_error!("you must not enable both `compio` and `tokio`");

sdgb-api/src/title/mod.rs

@@ -74,6 +74,9 @@ pub trait MaiVersionExt: MaiVersion {
         #[cfg(feature = "tokio")]
         use tokio::task::spawn_blocking;
 
+        #[cfg(all(not(feature = "compio"), not(feature = "tokio")))]
+        compile_error!("you must enable one of `compio` or `tokio`");
+
         async {
             let req = spawn_blocking(move || Self::api_call(api, agent_extra, data))
                 .await