Add start_server.sh script for dedicated headless server support

[Copilot]

This PR adds comprehensive dedicated server support for the cwagecraft modpack by implementing a start_server.sh script and updating the README with detailed server documentation.

Key Features

Automated Server Setup:

• Downloads and installs Forge server (MC 1.20.1 + Forge 47.3.22) automatically
• Intelligently filters and downloads only server-compatible mods (121 mods)
• Excludes client-only mods (9 mods: shaders, overlays, UI enhancements)
• Copies all mod configurations and datapacks to server
• Configures server.properties with sensible defaults
• Automatically accepts EULA for headless operation

Multiple Operation Modes:

./start_server.sh          # Setup and start server
./start_server.sh setup    # Setup only without starting
./start_server.sh test     # Analyze mod compatibility (dry run)
./start_server.sh clean    # Remove server files
./start_server.sh version  # Show version and status info

Robust Implementation:

• Color-coded logging for better user experience
• Retry logic for failed downloads with exponential backoff
• Comprehensive error handling and user guidance
• Optimized JVM arguments for server performance
• Generates helper scripts for manual server restarts

Documentation Enhancements

Updated README.md with complete server administration guide:

• Prerequisites: Java 17+ installation instructions for Ubuntu/Debian
• System Requirements: RAM, CPU, storage, and network requirements
• Setup Process: Step-by-step server installation guide
• Firewall Configuration: UFW and iptables examples for port 25565
• Server Management: Starting, stopping, monitoring commands
• Troubleshooting: Common issues and solutions
• Configuration: Customization options and backup procedures

Technical Details

The script intelligently processes the packwiz mod configuration files to:

• Filter mods by side property ("both" and "server" included, "client" excluded)
• Download mods directly from their source URLs with hash verification
• Handle network failures gracefully with automatic retries
• Provide detailed progress tracking and error reporting

Mod Analysis Results:

• Server-compatible mods: 121 (all core tech, magic, and utility mods)
• Client-only exclusions: 9 (Embeddium, Oculus, Light Overlay, Mouse Tweaks, etc.)

The implementation follows the project's architecture by leveraging the existing packwiz configuration rather than duplicating mod management logic.

Fixes #46.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• maven.minecraftforge.net
  • Triggering command: curl -L -o server/forge-1.20.1-47.3.22-installer.jar REDACTED (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

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