fix: bug: dev-poll stale detection races with issue_claim — blocks freshly claimed issues (#471)

Add 60-second grace period to stale in-progress detection in dev-poll.sh.
When a poller sees an in-progress issue with no assignee/PR/lock, it now
checks the timeline API for when the label was added. If <60s ago, it
skips stale detection to allow the claiming agent time to finish its
assign+label sequence.

Also documents the intentional assign-before-label ordering in
issue_claim() that minimizes the race window.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

lib/issue-lifecycle.sh

@@ -102,7 +102,9 @@ issue_claim() {
     return 1
   fi
 
-  # Assign to self (Forgejo rejects if already assigned differently)
+  # Assign to self BEFORE adding in-progress label (issue #471).
+  # This ordering ensures the assignee is set by the time other pollers
+  # see the in-progress label, reducing the stale-detection race window.
   curl -sf -X PATCH \
     -H "Authorization: token ${FORGE_TOKEN}" \
     -H "Content-Type: application/json" \