Aireceipts

Patch: the auto-attach hook now fires on bare-HEAD branch publishes —
git push -u origin HEAD (and --force-with-lease / HEAD:refs/heads/<x> forms), the
dominant idiom for coding agents, previously classified as not-a-branch-publish and the
SPEC-0073 hook silently wrote no receipt ref. Root-caused from the org dogfood pilots
producing zero receipts (issue #228, PR #230): the sibling hook on the same event fired
while ours declined classification. The receipt ref slug always derives from the
resolved checked-out branch; detached HEAD still attaches nothing (fail-safe), and
tag/sha/receipt-ref/delete publishes stay excluded.

Also: docs — terminal-statusline pages now say what happens without tmux (silent
fallback + alternatives, #226) and add a shell-wrapper recipe so the statusline appears
whenever the agent launches (#225).