Rename the delegate and consultant roles to helper and expert

Architecture L9's role names, for the two roles with a direct
counterpart: the delegation role is now 'helper' and the ask_expert role
'expert', in RoleMap, configuration (roles.helper, roles.expert),
recorded events and tests. 'planner' and 'executor' stay distinct for
now; they become 'driver' when the new loop merges them (Development
Plan M2.3).

Configurations must rename their keys: nisse-dev.example.yaml and
tests/integration/nisse-test.yaml are updated here.

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

nisse-dev/tests/test_expert.py

@@ -25,8 +25,8 @@ from nisse_dev.state import StateStore
 ROLES = RoleMap(
     executor="llama3.2",
     planner="haiku",
-    delegate="haiku",
-    consultant="claude-haiku-4-5",
+    helper="haiku",
+    expert="claude-haiku-4-5",
 )
 
 GOOD = '{"answer": "Use SQLite; it is enough here.", "confidence": "high", "caveats": "Assumes one writer."}'
@@ -137,7 +137,7 @@ def test_consults_are_recorded_as_composite_events(store: StateStore) -> None:
     events = [e.event for e in store.read_events()]
     started = next(e for e in events if isinstance(e, DelegationStarted))
     completed = next(e for e in events if isinstance(e, DelegationCompleted))
-    assert started.role == "consultant"
+    assert started.role == "expert"
     assert started.brief == "q"
     assert completed.exit_status == "answered"