chore: migrate tests to use AwesomeAssertions library

[mcj-coder]

Summary

Migrate existing test suites to use the AwesomeAssertions library for improved fluent assertion syntax and better error messages.

Current State

All tests currently use standard xUnit Assert.* methods.

Proposed Changes

• Add AwesomeAssertions NuGet package to test projects
• Migrate assertion patterns from xUnit Assert.* to AwesomeAssertions fluent syntax
• Review and update test patterns for improved readability

Affected Tests

• GameTimeTests.cs
• GameTimeSpanTests.cs
• AttributeSetTests.cs
• AttributeValueTests.cs
• TraitSetTests.cs
• TraitValueTests.cs
• NeedsStateTests.cs
• NeedValueTests.cs
• CharacterTests.cs
• CharacterIdTests.cs

Acceptance Criteria

• AwesomeAssertions package added to test project
• All tests migrated to fluent assertion syntax
• All tests continue to pass
• Zero compiler warnings

Labels

type:chore