test(techdemo): assert generated event constant

Prove data-slhx-on event discovery reaches an example generated API by asserting the techdemo issue-lane drop event constant.

req: codegen/006

examples/techdemo/src/lib.rs

@@ -47,4 +47,10 @@ mod tests {
             ui::control_center::forms::launch_work.id()
         );
     }
+
+    // req: codegen/006
+    #[test]
+    fn techdemo_exports_generated_event_constants() {
+        assert_eq!(ui::issue_lane::events::drop, "drop");
+    }
 }