Project-level agent instructions destined for the cproof repo root.
Staged here while the layered context bundle settles; will move to
cproof in a follow-up.
Pins the cproof-context bundle to commit 22977846 and tells the agent
the load order: SKILL.md -> INDEX.md -> on-demand -> gotchas.md, plus
wip/<branch>.md when working on a listed feature branch.
