feat(python): add zeroclaw-tools companion package for LangGraph tool calling

- Add Python package with LangGraph-based agent for consistent tool calling
- Provides reliable tool execution for providers with inconsistent native support
- Includes tools: shell, file_read, file_write, web_search, http_request, memory
- Discord bot integration included
- CLI tool for quick interactions
- Works with any OpenAI-compatible provider (Z.AI, OpenRouter, Groq, etc.)

Why: Some LLM providers (e.g., GLM-5/Zhipu) have inconsistent tool calling behavior.
LangGraph's structured approach guarantees reliable tool execution across all providers.

python/zeroclaw_tools/tools/shell.py

@@ -0,0 +1,32 @@
+"""
+Shell execution tool.
+"""
+
+import subprocess
+
+from langchain_core.tools import tool
+
+
+@tool
+def shell(command: str) -> str:
+    """
+    Execute a shell command and return the output.
+
+    Args:
+        command: The shell command to execute
+
+    Returns:
+        The command output (stdout and stderr combined)
+    """
+    try:
+        result = subprocess.run(command, shell=True, capture_output=True, text=True, timeout=60)
+        output = result.stdout
+        if result.stderr:
+            output += f"\nSTDERR: {result.stderr}"
+        if result.returncode != 0:
+            output += f"\nExit code: {result.returncode}"
+        return output or "(no output)"
+    except subprocess.TimeoutExpired:
+        return "Error: Command timed out after 60 seconds"
+    except Exception as e:
+        return f"Error: {e}"