Threads, commands and labels on the new loop (M2.3)

- Commands that name their item ("go #14", "abandon #14", "stop #14")
  apply to it wherever they're said; go, approve and abandon alone at top
  level are asked about (L5). stop is never taken as an answer.
- A plain-language reply to a restatement is read by GoAheadReader, one
  model call that agrees only on a clear yes; questions never reach it. The
  agent says "taking that as a go-ahead on rev-N" first, bound to the
  revision on screen at arrival (L3, L5, D1).
- Labels steer (D1): `bug` goes ahead after tuning.loop.bug_grace_s
  (default 600 s) unless the operator replies; `discuss` isn't offered
  restate until the operator has spoken; `bug`, `discuss` and `design` add
  to the driver's instructions. A restatement asks no questions.

Tests: label and command unit tests, the property walk with labelled
issues, plain yeses, named gos and time passing (grace_only_unanswered,
discuss_talks_first), and e2e tests for a bug proceeding after its grace
period and a plain-language go-ahead.

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

nisse-dev/tests/test_config.py

@@ -158,6 +158,7 @@ def test_tuning_is_read() -> None:
             "expert": {"consult_budget": 5},
             "delegation": {"max_turns": 20, "max_tokens": 100000, "wall_clock_s": 600},
             "tools": {"command_timeout_s": 300, "max_output_chars": 2000},
+            "loop": {"bug_grace_s": 120},
         }
     )
     tuning = config.tuning
@@ -166,6 +167,7 @@ def test_tuning_is_read() -> None:
     assert tuning.delegation.max_tokens == 100_000
     assert tuning.delegation.wall_clock_s == 600.0
     assert tuning.tools.max_output_chars == 2000
+    assert tuning.loop.bug_grace_s == 120.0
 
 
 def test_a_partly_given_tuning_section_keeps_the_other_defaults() -> None: