[dev-kit] dev-embedded/arduino-bin autogen fails

```
ERROR Errors were encountered when processing the following autogens:
ERROR *
/home/tree/repo_tmp/source-trees/kit-fixups/dev-kit/curated/dev-embedde
d/arduino-bin/autogen.py (dev-embedded/arduino-bin)
ERROR * dev-util/datagrip-2025.2
ERROR End of report.
[?25h
ERROR Command failure from merge-kits: cd
/home/tree/repo_tmp/source-trees/kit-fixups/dev-kit/curated && doit
--fast --release next --fastpull_scope=local --moonbeam --prod
CRITICAL Step Autogen failed with Exception: failed autogen in
/home/tree/repo_tmp/source-trees/kit-fixups -- offset dev-kit/curated.
ERROR Kit job failure:
Traceback (most recent call last):
File "/usr/lib/python3.9/site-packages/metatools/kit.py", line 678,
in run
await method()
File "/usr/lib/python3.9/site-packages/metatools/kit.py", line 470,
in generate
await self.generate_autogenerated()
File "/usr/lib/python3.9/site-packages/metatools/kit.py", line 417,
in generate_autogenerated
await self.run(self.autogen_and_copy_from_kit_fixups())
File "/usr/lib/python3.9/site-packages/metatools/kit.py", line 159,
in run
raise e
File "/usr/lib/python3.9/site-packages/metatools/kit.py", line 156,
in run
await step.run(self)
File "/usr/lib/python3.9/site-packages/metatools/steps.py", line 415,
in run
await self.srctree.autogen(src_offset=self.ebuildloc,
scope=self.scope)
File "/usr/lib/python3.9/site-packages/metatools/tree.py", line 88,
in autogen
raise GitTreeError(f"failed autogen in {self.root} -- offset
{src_offset}.")
metatools.tree.GitTreeError: failed autogen in
/home/tree/repo_tmp/source-trees/kit-fixups -- offset dev-kit/curated.
[?25h
```

Start with dev-kit/curated/dev-embedded/arduino-bin/autogen.py and reproduce the failure through the shown merge-kits command using doit. Trace the autogen path through metatools/kit.py, metatools/steps.py, and metatools/tree.py; done means the arduino-bin autogen completes without the reported GitTreeError.

Written by the indexing model from the issue text.