fix(cli): derive actor name from config file instead of positional argument

Remove the <NAME> positional argument from `actor add` command. The actor
name is now derived from the `name` field inside the config YAML file, per
the specification: `agents actor add (--config|-c) <FILE> [--update]`.
Updated all BDD and integration tests to pass name via config file.

ISSUES CLOSED: #914

benchmarks/actor_cli_bench.py

@@ -34,6 +34,7 @@ from cleveragents.cli.commands.actor import app as actor_app  # noqa: E402
 from cleveragents.domain.models.core.actor import Actor  # noqa: E402
 
 _VALID_CONFIG = {
+    "name": "local/bench",
     "provider": "openai",
     "model": "gpt-4",
     "temperature": 0.5,
@@ -84,7 +85,7 @@ class ActorCLIAddSuite:
 
     def time_add_from_config(self) -> None:
         """Benchmark add --config end-to-end."""
-        _runner.invoke(actor_app, ["add", "local/bench", "--config", self._path])
+        _runner.invoke(actor_app, ["add", "--config", self._path])
 
 
 class ActorCLIListSuite: