M2.8: switch over to the new loop

nisse-dev now runs only the conversational loop. The gated state machine
it was built alongside is gone:

- Removed control.py, planner.py, executor.py, approvals.py, gates.py
  (command_form moves to loop/reader.py), publish.py and poller.py, the
  old assembly in agent.py (its shared helpers move to loop/build.py),
  the store's state-machine view (get_state, transition), their tests,
  the old end-to-end and live planning/milestone/gate tests, and
  specs/orchestrator.qnt with its scenarios.
- Roles are driver, helper, expert and classifier; driver is required.
  loop:, roles.planner, roles.executor and tuning.executor are refused
  with what to use instead; tuning.driver takes the turn cap and failure
  limit.
- The benchmark and the capability matrix measure the driver: the
  loop's own system prompt and tools, the task's plan as the agreed
  restatement. Task plans end with finish_milestone, so earlier runs
  show as (old); stored runs' executor tuning reads as the driver's.
- A delegation on the loop records what its helper's alias resolved to
  (L9), as the old path's did.
- The dump shows a work item's revision and what it waits for.
- Behaviour the old tests covered and the loop shares stays covered:
  driver runs that fail on a model call, stop mid-turn, reset the
  failure count; go-aheads ignoring case and punctuation; a request too
  big to fit is never sent; the assembly tests, now on build_loop_agent.

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

tests/integration/test_llm_live.py

@@ -11,7 +11,7 @@ from nisse_dev.llm import LiteLLMClient
 pytestmark = pytest.mark.integration
 
 
-def test_executor_model_completes_via_litellm(
+def test_the_driver_model_completes_via_litellm(
     litellm: LiteLLMClient, live_config: AgentConfig
 ) -> None:
     events = [
@@ -23,7 +23,7 @@ def test_executor_model_completes_via_litellm(
             ),
         )
     ]
-    result = litellm.complete(events, tools=None, model=live_config.roles.executor)
+    result = litellm.complete(events, tools=None, model=live_config.roles.driver)
     texts = [e.text for e in result if isinstance(e, AssistantText)]
     assert texts, f"no assistant text in {result!r}"
     # A plumbing check, so any answer will do: what the model chooses to say
@@ -41,7 +41,7 @@ def test_declared_limits_reach_a_budgeted_request(
     roles = live_config.roles.pinned()
     catalog.require_limits(roles)  # every test role has a declared window
 
-    model = live_config.roles.executor
+    model = live_config.roles.driver
     facts = catalog.facts(model)
     client = BudgetedClient(
         litellm,