feat: auto-select single server and remove local execution

[michelroegl-brunner]

Overview

This PR implements automatic server selection when only one server is configured and removes the local execution option entirely.

Changes Made

✨ New Features

• Auto-select single server: When exactly one server is configured, the execution modal is bypassed and the script runs immediately
• Server settings integration: Added button to open server settings directly from execution modal when no servers are configured
• Auto-refresh: Server list automatically refreshes when settings modal closes

🔧 Improvements

• Removed local execution: All scripts now execute via SSH only, simplifying the execution flow
• Updated modal title: Changed from 'Execution Mode' to 'Select Server' to better reflect functionality
• Streamlined UI: Removed execution mode selection, focusing only on server selection

🐛 Bug Fixes

• Cleaned up debug messages that were appearing in terminal output

Behavior Changes

• 0 servers: Modal shows with message that servers are required + 'Open Server Settings' button
• 1 server: Modal is skipped entirely, script immediately starts on that server via SSH
• 2+ servers: Modal shows with server selection dropdown, user selects which server to use

Testing

• Single server setup - auto-execution works
• Multiple servers - manual selection works
• No servers - settings button appears
• Settings integration - server list refreshes after adding servers

This provides a much smoother user experience, especially for single-server setups, while maintaining full functionality for multi-server environments.