fix: harden API macro expansion hygiene

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

@@ -0,0 +1,14 @@
+use api_macros::api;
+
+pub struct Response;
+
+#[api]
+pub trait MarkerCollision {
+    #[get("/first")]
+    async fn foo_bar(&self) -> Response;
+
+    #[get("/second")]
+    async fn foo__bar(&self) -> Response;
+}
+
+fn main() {}