LocalSandbox.exec: accept entrypoint kwarg (signature parity)

The entrypoint override added only DockerSandbox the parameter; the
execution scorer now always passes it, so every local-sandbox bench
(live_code_bench) died with 'got an unexpected keyword argument' and
scored 0. Accepted (and ignored) in local/base for parity.

Co-Authored-By: Claude <noreply@anthropic.com>

evalharness/sandbox/base.py

@@ -65,6 +65,8 @@ class Sandbox:
         mounts: Optional[Dict[str, str]] = None,
         timeout_s: int = 60,
         image: str = '',
+        entrypoint: str = '',   # docker-only override; accepted for
+                                # signature parity (local runs a plain python)
     ) -> ExecResult:
         """Run ``python <entry>`` with ``files`` (name->content) in isolation.
 

evalharness/sandbox/local.py

@@ -25,6 +25,8 @@ class LocalSandbox(Sandbox):
         mounts: Optional[Dict[str, str]] = None,
         timeout_s: int = 60,
         image: str = '',
+        entrypoint: str = '',   # docker-only override; accepted for
+                                # signature parity (local runs a plain python)
     ) -> ExecResult:
         with tempfile.TemporaryDirectory(prefix='eh-local-') as td:
             work = Path(td)