Clarify that index.test.ts is an orchestration unit test, not integration

[maximn]

src/__tests__/index.test.ts is described as an "integration test for the full run() pipeline", but it mocks @actions/core, node:fs, the parsers, the API client, and utils — so it verifies run() orchestration with everything stubbed, not real module integration.

True integration coverage lives in .github/workflows/e2e.yml (uses: ./ against fixtures) and the ci.yml self-test.

Suggested fix

• Update the description / CLAUDE.md wording so the test layers aren't misrepresented.
• Optionally add a thin real-integration test that exercises unmocked modules.

Minor.

Flagged during the AI-native docs revamp; tracked in .agents/known-issues.md (item F).