Tests for Service functions.

[WoodrowKromar]

#8560

• Test files covering the major services of the Steam Leak Calculator and Treasure hunt implementations.
• Ran and confirmed successful.
• Base-level unit tests, no integration.

Pull Request Template

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• Variable, function, and class names are descriptive
• Code leverages existing architecture, helper methods, and shared modules when applicable
• Development artifacts such as console logs, test values, and comments have been removed
• All Copilot, Claude Code, or other LLM implementations have been reviewed as if contributed by another developer
• UI changes have been manually tested for usability and appearance
• This PR references the related issue number (if applicable), ex. issue -> #0000

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