Patch fix

Bug fixes, additional logical validations, and data flow control improvements. It also adds tests for existing functionality to ensure stability and correctness.

What's Changed

• Migrate Rails 7 to Rails 8 by @Kagayakashi in #18
• Characters refactor by @Kagayakashi in #19
• Tests and refactoring for core functionality by @Kagayakashi in #20
• fix: refactor combat and rewards by @Kagayakashi in #21

Full Changelog: v0.1.0-alpha...v0.1.1-alpha