fix: Enable and stabilize CI test execution

[Patrick-Ehimen]

Summary

Tests are currently disabled in the CI pipeline (ci.yml:84) with a TODO: Re-enable tests once test suite is stabilized. This means PRs merge without any automated test validation, giving false confidence in code quality.

Problem

1. CI tests disabled — The test job in .github/workflows/ci.yml (line 84) is commented out
2. SDK wrapper tests broken — Two test blocks in packages/sdk-wrapper/src/__tests__/LighthouseAISDK.test.ts are skipped:
   • Line 51: TODO: Fix authentication mocking - tests require proper fetch/auth mock setup
   • Line 83: TODO: Fix fs mock - missing readFileSync and other fs methods
3. No test gate on PRs — Branch protection has no passing test requirement

Acceptance Criteria

• Fix SDK wrapper test mocking (auth and fs mocks)
• Re-enable the test job in ci.yml
• All existing tests pass in CI (both Jest and Vitest suites)
• Branch protection requires passing tests before merge

Files to Modify

• .github/workflows/ci.yml (line 84–104)
• packages/sdk-wrapper/src/__tests__/LighthouseAISDK.test.ts
• Possibly apps/mcp-server/vitest.config.ts for coverage thresholds

Context

• MCP server uses Vitest (85% line / 90% function / 85% branch targets)
• All other packages use Jest with ts-jest
• 47 test files exist across the codebase — most pass individually but CI integration is broken