[Docs] Add example test CVs for local development #50

Add 3-5 sample CVs in packages/core/src/__fixtures__/ as markdown files for contributors to test against locally.

Include a mix:

1. good-backend.md - A strong backend engineer CV (should score 4+)
2. weak-generic.md - A buzzword-heavy generic CV (should score 2 or below)
3. ai-engineer.md - An AI engineer CV with quantified metrics
4. missing-metrics.md - Decent experience but no numbers anywhere
5. career-changer.md - Someone transitioning into tech

These are fictional CVs used only for testing. Do not use real people's data.

Also add a sample JD file (sample-jd.md) so contributors can test keyword matching.