feat: Initial library extraction from PIN LLM benchmark

DockerSandbox + LangChain file/shell tools extracted into a standalone package.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker_agent_sandbox/tools/delete_file.py

@@ -0,0 +1,33 @@
+"""delete_file.py – tool for deleting files inside the sandbox."""
+
+from __future__ import annotations
+
+from shlex import quote
+from typing import TYPE_CHECKING
+
+from langchain_core.tools import BaseTool, tool
+from loguru import logger
+
+if TYPE_CHECKING:
+    from docker_agent_sandbox.sandbox import DockerSandbox
+
+
+def make_delete_file_tool(sandbox: "DockerSandbox") -> BaseTool:
+    """Return a delete_file tool bound to *sandbox*."""
+
+    @tool
+    def delete_file(path: str) -> str:
+        """
+        Delete a file or empty directory at *path*.
+
+        Use ``delete_file`` only for files or empty directories.  To remove a
+        directory tree use ``move_file`` to archive it first, or call this tool
+        repeatedly.  Returns a confirmation message or an error.
+        """
+        logger.debug("Deleting file inside sandbox: {}", path)
+        exit_code, output = sandbox.exec(f"rm -d -- {quote(path)}")
+        if exit_code != 0:
+            return f"[ERROR deleting {path!r}] {output.strip()}"
+        return f"[OK] Deleted {path}"
+
+    return delete_file