Add SSH MCP server and Gmail attachment download

Features:
- SSH MCP server with two tools:
  * ssh_execute: Run commands on remote hosts via SSH
  * ssh_file_upload: Upload files via SFTP
- Support for both password and SSH key authentication
- Auto-accept SSH host keys (AutoAddPolicy) for homelab use
- Gmail attachment download functionality
- Added download_attachment tool for Gmail API

Technical changes:
- Created mcp_servers/mcp_ssh.py with MCP-compliant text output
- Updated llm_interface.py to load SSH MCP server
- Added paramiko>=3.4.0 to requirements.txt
- Updated .env.example with SSH configuration template
- Enhanced gmail_client.py with download_attachment() method
- Added download_attachment tool handler in tools.py

SSH credentials configured via environment variables:
- PROXMOX_SSH_HOST, PROXMOX_SSH_USER, PROXMOX_SSH_PORT
- PROXMOX_SSH_PASSWORD (or) PROXMOX_SSH_KEY_FILE

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

requirements.txt

@@ -32,3 +32,6 @@ python-dotenv>=1.0.0
 # Web fetching dependencies
 httpx>=0.27.0
 beautifulsoup4>=4.12.0
+
+# SSH dependencies
+paramiko>=3.4.0