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_catalog.py

@@ -130,13 +130,13 @@ def test_validate_names_every_bad_role_at_once() -> None:
             {
                 "executor": "local-fast",
                 "planner": "clause-opus-5",
-                "delegate": "remote-architecture",
-                "consultant": "local-fast",
+                "helper": "remote-architecture",
+                "expert": "local-fast",
             }
         )
     message = str(caught.value)
     assert "planner='clause-opus-5'" in message
-    assert "delegate='remote-architecture'" in message
+    assert "helper='remote-architecture'" in message
     assert "executor" not in message  # the good ones are not noise