[CLI] Add --archetype flag to override detection #20

Add --archetype <id> flag to force a specific role type instead of auto-detection.

Usage:

cv-builder evaluate cv.md --archetype ai-engineer
cv-builder evaluate cv.md --archetype devops-sre

Implementation:

• Accept the flag in CLI argument parsing
• Pass it to evaluate({ archetype: value })
• Show error with available archetypes if invalid ID provided
• Add --archetype to help text