feat: add custom seed argument for deterministic generation #120

What type of contribution is this?

feat

Description of the feature

Currently, it is not possible to specify a particular seed at startup.
To ensure 100% deterministic behavior and allow users to share worlds, it must be possible to launch the executable with a specific seed (e.g., cargo run -- 418) in order to reproduce the exact same star system.

If no argument is provided at startup, the program must generate a new random seed.

🎯 Expected behavior

• The program reads the first argument passed via the CLI.
• If an argument is provided: it is converted into an integer and used as the seed.
• If the argument is missing (or invalid): the program generates a random seed.
• The final seed used for generation is displayed in the console/logs so the user can note it down and reuse it later.

Contribution

• Yes, I want to work on this and submit a Pull Request!