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_context.py

@@ -262,7 +262,7 @@ def test_the_executor_sees_only_its_milestone(tmp_path: Path) -> None:
             seen["system"] = system
             return [AssistantText(text="done", model=model)]
 
-    roles = RoleMap(executor="m", planner="m", delegate="m", consultant="m")
+    roles = RoleMap(executor="m", planner="m", helper="m", expert="m")
     LLMExecutor(Client(), store, roles, Workspace()).run(1)
 
     texts = [getattr(e, "text", None) for e in seen["events"]]
@@ -286,7 +286,7 @@ def test_a_request_that_cannot_fit_stops_the_milestone(tmp_path: Path) -> None:
 
     inner = RecordingClient()
     client = BudgetedClient(inner, lambda m: (4096, 1024))
-    roles = RoleMap(executor="m", planner="m", delegate="m", consultant="m")
+    roles = RoleMap(executor="m", planner="m", helper="m", expert="m")
     outcome = LLMExecutor(client, store, roles, Workspace()).run(1)
 
     assert outcome.status == "escalate"