Fixes from the rest of the live session

- A near miss for abandon ("abort", "cancel", "drop it", ...) in an item's
  thread is asked about, and changes nothing.
- The driver is told only the operator stops or closes an item, so it
  doesn't claim to have done either.
- An issue assigned again after its item closed starts a new item that
  notes the one before (Gitea's timeline gives the assignment time);
  item_for_issue returns the latest item.
- Abandoning an issue Gitea won't close because of open dependencies says
  so, naming them.
- An agreed item isn't offered restate.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPQ14L3LikyefCMFBqEbKE

nisse-dev/src/nisse_dev/gitea.py

@@ -261,6 +261,31 @@ class GiteaClient:
                 who = (event.get("user") or {}).get("login")
         return who
 
+    def assigned_at(self, repo: str, index: int, assignee: str) -> str | None:
+        """When the issue was last assigned to ``assignee`` (ISO 8601), from
+        its timeline, oldest first and paged to the end; None if the
+        timeline doesn't say."""
+        when = None
+        for page in range(1, MAX_PR_PAGES + 1):
+            events = (
+                self._request(
+                    "GET",
+                    f"/repos/{repo}/issues/{index}/timeline",
+                    params={"limit": PR_PAGE_SIZE, "page": page},
+                )
+                or []
+            )
+            for event in events:
+                if (
+                    event.get("type") == "assignees"
+                    and not event.get("removed_assignee")
+                    and (event.get("assignee") or {}).get("login") == assignee
+                ):
+                    when = event.get("created_at")
+            if len(events) < PR_PAGE_SIZE:
+                break
+        return when
+
     def repository(self, repo: str) -> dict[str, Any]:
         """The repository as this account sees it, permissions included."""
         return dict(self._request("GET", f"/repos/{repo}"))