feat: add typed conditional API responses

crates/api-macros/tests/ui/not_modified_body.rs

@@ -0,0 +1,14 @@
+use api_macros::api;
+
+pub struct Body;
+
+#[api]
+pub trait NotModifiedBodyApi {
+    #[get(
+        "/not-modified",
+        responses = [(status = 304, body = Body)]
+    )]
+    async fn not_modified(&self) -> not_modified_body_api_responses::NotModified;
+}
+
+fn main() {}