Conversation on the new loop (M2.7)

- Questions never change state (L5, #77): a message ending in "?" to a
  waiting project item starts a question run (reply and look-only tools,
  an instruction to change nothing), and the item goes back to the very
  wait it was in: a restatement up stays up and a go binds to it; the
  agent's own question stays open.
- Explanations: a restatement gives its reasons and the main alternative;
  a revision says what changed (restate(changed), sent back without it);
  a milestone's summary says what was done, verified and left open.
- Progress in prose (#42): the driver's and a helper's own words for a
  turn are posted, trimmed, at most once a minute per item; `details`
  shows the last tool calls; a message arriving mid-run is acknowledged at
  once ("Noted; ...").
- CI: the e2e job's comments and the plan no longer claim a newer push
  cancels the run it supersedes (Gitea here doesn't); the concurrency
  block goes.

Tests: conversation unit tests (questions in a go-ahead and an answer wait,
an unanswerable question, revisions, progress rate and trimming, details,
mid-run notes), the helper's progress, the walk asking questions in every
state with a questions_change_nothing property (routing questions the old
way fails 32 of 48 seeds), and an e2e question while a restatement is up.

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

nisse-dev/tests/test_loop_multi.py

@@ -95,7 +95,7 @@ def test_the_next_milestone_waits_for_the_merge(world: dict[str, Any]) -> None:
     agent, transport = loop_agent(world, model)
     agent.intake()
     say(transport, world, "go")
-    say(transport, world, "how's it going?")
+    say(transport, world, "carry on")
     assert "hasn't merged yet" in result_of(world, "start_milestone")
     assert (item(world).position, loop_of(item(world)).wait) == (WAITING, MERGE)
     assert len(forge.prs) == 1