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/src/nisse_dev/llm.py

@@ -109,10 +109,10 @@ class LLMClient(Protocol):
 class RoleMap:
     executor: str
     planner: str
-    delegate: str
-    consultant: str
+    helper: str
+    expert: str
 
-    ROLES: ClassVar[tuple[str, ...]] = ("executor", "planner", "delegate", "consultant")
+    ROLES: ClassVar[tuple[str, ...]] = ("executor", "planner", "helper", "expert")
 
     def resolve(self, role: str) -> str:
         if role not in self.ROLES: