onlydiffs v0.1.13

Release v0.1.13

v0.1.12 built cleanly four times over and could not be published: a run
inherits the token permissions it was created with, so every attempt from
that tag carried the read-only snapshot from before the repository setting
was changed, and a re-run does not pick up the new one. A fresh tag is the
only thing that reads it.

This one is also the first release to use the workflow it is built by,
rather than the one the previous tag froze — so it restores the cache that
CI now leaves on main instead of building everything from nothing.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Dm8xs3PrMFCKhKHLQT7EN1