CodeRabbit Generated Unit Tests: Add Vitest testing infrastructure and test suites

[gowtham-kishore-dev]

Unit test generation was requested by @gowthamkishore3799.

• adding changes #970 (comment)

The following files were modified:

• fools/files.test.ts
• fools/trails.test.ts
• tsconfig.json
• vitest.config.ts

[coderabbitai]

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