Update environment configuration and enhance terminal tool integration

- Updated `.env.example` to include new API keys and configuration options for the mini-swe-agent backend, including support for local, Docker, and Modal environments.
- Added `.gitmodules` to include mini-swe-agent as a submodule for easier integration.
- Refactored `mini_swe_runner.py` to use the updated model format and default to OpenRouter for API calls.
- Enhanced `model_tools.py` to support the new terminal tool definitions and ensure compatibility with the mini-swe-agent backend.
- Updated `README.md` to reflect changes in setup instructions and environment variable configurations.
- Improved `terminal_tool.py` to manage execution environments and lifecycle, ensuring proper cleanup and error handling.
- Introduced `terminal_hecate.py` for executing commands on MorphCloud VMs, providing an alternative backend for terminal operations.

mini_swe_runner.py

@@ -149,7 +149,7 @@ class MiniSWERunner:
     
     def __init__(
         self,
-        model: str = "claude-sonnet-4-20250514",
+        model: str = "anthropic/claude-sonnet-4-20250514",
         base_url: str = None,
         api_key: str = None,
         env_type: str = "local",
@@ -189,14 +189,18 @@ class MiniSWERunner:
         )
         self.logger = logging.getLogger(__name__)
         
-        # Initialize OpenAI client
+        # Initialize OpenAI client - defaults to OpenRouter
         from openai import OpenAI
         
         client_kwargs = {}
+        
+        # Default to OpenRouter if no base_url provided
         if base_url:
             client_kwargs["base_url"] = base_url
+        else:
+            client_kwargs["base_url"] = "https://openrouter.ai/api/v1"
         
-        # Handle API key with fallbacks
+        # Handle API key - OpenRouter is the primary provider
         if api_key:
             client_kwargs["api_key"] = api_key
         else: