The queue: parking, the operator's order, blocked items (M2.2)

Several work items on the new loop (L1, D4):
- Switching parks the item on the workspace: its work is committed and its
  branch pushed; resuming checks the item's branch back out. Branches of
  open items are never set aside by a fresh workspace.
- Next item: the operator's "do #N next" first, otherwise the oldest.
- Issues with open Gitea dependencies are blocked until they close, checked
  at intake and on every round; status shows blocked items and the line.

Tests: queue unit tests, the property walk over several issues with
dependencies and a new parked_work_safe property (it catches parking
disabled), and an end-to-end test with two issues where B depends on A.

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

tests/integration/e2e_support.py

@@ -17,6 +17,15 @@ def task(run: str) -> str:
     )
 
 
+def dependent_task(run: str) -> str:
+    """A request that builds on task(run): it can only be done after it."""
+    return (
+        f"Add a function consonants_{run}(text) to the sandbox package that "
+        "returns how many letters in the text are not vowels, using "
+        f"vowels_{run}, with tests."
+    )
+
+
 def operator_gitea(url: str) -> GiteaClient:
     token = os.environ.get("NISSE_OPERATOR_TOKEN", "")
     assert token.strip(), (