Let the live milestone test expect a waiting state after execution

It drove the orchestrator until EXECUTING and accepted EXECUTING as the
end state, which with no publisher configured was the stranding this
branch removes: the milestone now finishes in PR_OPEN. Return once
'start milestone 1' is sent, since the milestone runs inside it, and
expect PR_OPEN or AWAIT_INPUT.

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

tests/integration/test_milestone_live.py

@@ -16,6 +16,7 @@ from nisse_dev.control import (
     AWAIT_INPUT,
     AWAIT_MILESTONE_SIGNOFF,
     EXECUTING,
+    PR_OPEN,
     Orchestrator,
 )
 from nisse_dev.executor import LLMExecutor
@@ -45,7 +46,9 @@ def _drive_to_execution(
         if state.state == AWAIT_INPUT:
             transport.receive("don", "Use your best judgement and proceed.")
         elif state.state == AWAIT_MILESTONE_SIGNOFF and gate.get("approved"):
+            # The milestone runs to completion inside this command.
             transport.receive("don", "start milestone 1")
+            return
         elif state.state in (AWAIT_ARCH_SIGNOFF, AWAIT_MILESTONE_SIGNOFF):
             transport.receive("don", "approve")
         else:
@@ -85,7 +88,9 @@ def test_plan_approve_execute_produces_a_real_file(
 
     state = store.get_state()
     assert state is not None
-    assert state.state in (EXECUTING, AWAIT_INPUT)
+    # Never EXECUTING at rest: with no publisher a finished milestone waits in
+    # PR_OPEN, and one that stopped short waits for the operator.
+    assert state.state in (PR_OPEN, AWAIT_INPUT)
 
     created = list(workspace.root.rglob("*.py"))
     assert created, f"executor created no Python file; said: {transport.outbound[-1]}"