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

nisse-dev/src/nisse_dev/loop/items.py

@@ -13,6 +13,7 @@ from nisse_dev.state import StateStore, WorkItem
 READY = "ready"
 RUNNING = "running"  # a driver run is under way; on boot it means interrupted
 WAITING = "waiting"
+BLOCKED = "blocked"  # waits for its recorded dependencies to close (L1)
 CLOSED = "closed"
 
 # What a waiting item waits for.
@@ -25,7 +26,7 @@ MERGE = "merge"  # the PR's review and merge (D4, D5)
 class Loop:
     thread: str = ""  # the root of the item's Matrix thread (L5)
     issue: int = 0  # its record issue (D1)
-    wait: str = ""  # GO_AHEAD / ANSWER, when waiting
+    wait: str = ""  # GO_AHEAD / ANSWER / MERGE, when waiting
     rev: int = 0  # the latest proposal put up (L3)
     started: bool = False  # scope agreed: a go-ahead was given (D1)
     note: str = ""  # what a waiting item said it is waiting on
@@ -37,6 +38,8 @@ class Loop:
     comments: int = 0  # the last PR conversation comment taken (L8)
     notes: tuple[str, ...] = ()  # review notes taken (#69)
     fixes: int = 0  # review fixes pushed, for follow-up branch names
+    blocked_by: tuple[str, ...] = ()  # open dependencies, "owner/repo#N" (L1)
+    first: int = 0  # the operator's "do #N next": higher runs sooner
     # Where the operator last spoke (D5: answer where asked): "" for the
     # Matrix thread, or the PR it came from, with the inline location and a
     # little of what they said, for quoting.
@@ -51,6 +54,7 @@ class Loop:
 def loop_of(item: WorkItem) -> Loop:
     data = dict(item.data.get("loop", {}))
     data["notes"] = tuple(data.get("notes", ()))
+    data["blocked_by"] = tuple(data.get("blocked_by", ()))
     return Loop(**data)