New test classes:
- TestSessionLifecycle: /new then /status sequence, idempotent resets
- TestAuthorization: unauthorized users get pairing code, not commands
- TestSendFailureResilience: pipeline survives send() failures
Additional command coverage: /provider, /verbose, /personality, /yolo.
Note: /provider test is xfail - found a real bug where model_cfg is
referenced unbound when config.yaml is absent (run.py:3247).
Fixtures and helpers for driving messages through the full async
pipeline: adapter.handle_message → background task → GatewayRunner
command dispatch → adapter.send (mocked).
Uses the established _make_runner pattern (object.__new__) to skip
filesystem side effects while exercising real command dispatch logic.
