try to use generate script

the script fails with:
Couldn't resolve the package 'ffigen' in 'package:ffigen/ffigen.dart'.
Couldn't resolve the package 'path' in 'package:path/path.dart'.

flake.nix

@@ -84,6 +84,11 @@
               flyer_chat_text_message = "sha256-4fuag7lRH5cMBFD3fUzj2K541JwXLoz8HF/4OMr3uhk=";
               window_size = "sha256-XelNtp7tpZ91QCEcvewVphNUtgQX7xrp5QP0oFo6DgM=";
             };
+
+            patchPhase = /* sh */ ''
+              patchShebangs ./scripts/generate.sh
+              ./scripts/generate.sh # note: this doesn't quit the build on fail
+            '';
           };
         };
     };