Migrate test framework from Jest to Vitest

[Copilot]

This PR migrates the project's testing framework from Jest to Vitest while preserving all existing test functionality and behavior.

Changes Made

Dependencies Updated

• Removed: jest, ts-jest, @types/jest, eslint-plugin-jest
• Added: vitest, @vitest/ui, eslint-plugin-vitest, @types/node

Configuration Files

• Replaced jest.config.js with vitest.config.ts using equivalent configuration
• Updated tsconfig.test.json to use vitest/globals types instead of jest
• Updated eslint.config.js to use eslint-plugin-vitest instead of eslint-plugin-jest
• Updated tsconfig.json to exclude vitest.config.ts from main build

Test Code Migration

Updated __tests__/generate-sbom.test.ts to use Vitest APIs:

• Changed imports from '@jest/globals' to 'vitest'
• Replaced jest.mock() with vi.mock()
• Replaced jest.fn() with vi.fn()
• Replaced jest.spyOn() with vi.spyOn()
• Replaced jest.clearAllMocks() with vi.clearAllMocks()

Package Scripts

Updated package.json scripts:

• "test": "vitest run" (was "jest")
• "btest": "npm run build & vitest run" (was "npm run build & jest")

Verification

✅ All existing tests continue to pass with identical behavior
✅ Build process works correctly (npm run build)
✅ Linting passes (npm run lint)
✅ Full workflow succeeds (npm run all)
✅ Test output format is clean and informative

The migration maintains 100% compatibility with existing test logic while providing the benefits of Vitest (faster execution, better TypeScript support, and modern ESM compatibility).

Fixes #108.

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