a symlink into a local build cache reached `main`, and is removed

Agent-decided, reversible; a scrub. The consolidation pass above planted a symlink at the Lean build-cache path lean/.lake, pointing at another checkout's cache to avoid refetching Mathlib; the ignore pattern lean/.lake/, with a trailing slash, covered directories only, so staging everything picked the symlink up and it landed in the Normative Inductor squash (caa3ad0). CI stayed green because the Lean job builds into that path regardless of what is at it. The symlink is removed and the ignore rule drops the trailing slash, so it matches a directory or a symlink. No content or theorem was affected; the defect is a path into one machine's filesystem in a public tree.

Rejected alternative: rewriting caa3ad0 — history is not rewritten here, and the squash message is correct about everything but this.