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

tests/integration/test_planning_live.py

@@ -25,7 +25,7 @@ def test_live_planning_turn_returns_a_tool_action(
     tmp_path: Path, litellm: LiteLLMClient, live_model: str
 ) -> None:
     model = live_model
-    roles = RoleMap(executor=model, planner=model, delegate=model, consultant=model)
+    roles = RoleMap(executor=model, planner=model, helper=model, expert=model)
     store = StateStore(tmp_path / "state.db", oplog=OpLog("nisse-dev", io.StringIO()))
     store.append_event(
         UserMessage(