- Remove Jest dependencies (jest, @swc/jest, @types/jest)
- Remove Jest configuration from package.json
- Update test script to use 'bun test'
- Update test type definitions to use Bun's Mock type
- Migrate all 43 test files to Bun test syntax:
  - Replace jest.mock() with mock.module()
  - Replace jest.fn() with mock()
  - Replace jest.spyOn() with spyOn()
  - Convert static imports to dynamic imports (await import())
  - Add process.env.INPUT_GITHUB_TOKEN for test environment
  - Create comprehensive mockOctokit structure
  - Mock octokit module directly for proper test isolation

Current status:
- 87 tests passing (41%)
- 125 tests need mock implementation adjustments
- Some linting errors to be addressed in follow-up
- All files structurally migrated and executable with bun test

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>