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>

.env.example

@@ -35,6 +35,23 @@ AJARBOT_SLACK_APP_TOKEN=xapp-your-app-token
 # Get token from: https://t.me/BotFather
 AJARBOT_TELEGRAM_BOT_TOKEN=123456:ABC-your-bot-token
 
+# ========================================
+# SSH Access (Optional)
+# ========================================
+# Proxmox SSH credentials for remote management
+PROXMOX_SSH_HOST=192.168.2.100
+PROXMOX_SSH_USER=root
+PROXMOX_SSH_PORT=22
+
+# Authentication: Use EITHER password OR key (key is more secure)
+# Option 1: Password-based (easier but less secure)
+PROXMOX_SSH_PASSWORD=your-proxmox-password
+
+# Option 2: Key-based (recommended for security)
+# PROXMOX_SSH_KEY_FILE=C:/Users/YourName/.ssh/id_rsa
+# Generate key: ssh-keygen -t rsa -b 4096
+# Copy to Proxmox: ssh-copy-id root@192.168.2.100
+
 # ========================================
 # Obsidian MCP Integration (Optional)
 # ========================================