The nudge rode `last_issue_activity`, which counts `assigned` timeline
events because assignment is the claim the 48-hour reclaim protects.
`post-merge` has no claim: an assignee there is the invalid composition
the flag beside it reports, so counting the assignment let a broken board
buy the item another 7 days of silence — this issue's failure direction
taken backwards.
One computation, two clocks over it: `issue_activity_at` is the body,
`last_issue_activity` keeps the reclaim and ruling clocks byte-identical,
and `last_issue_comment_activity` is the evidence clock. Both clocks are
read before this branch posts anything, the ruling one included — read
after, it would date the issue by the evidence nudge's own comment and
silence the ruling nudge, which is the self-silencing the branch already
guarded against in the other direction.
Refs #254
d4a82707f2