Fix stale settled paths after hoagie data update

[DIodide]

Summary

• Adds clear_settled_paths management command to clear stale settled paths from all user schedules after the hoagie requirements data update (Feat/hoagie requirements data #514) changed category names
• Adds POR (Portuguese) and SPA (Spanish) to AB_CONCENTRATIONS and creates their Major DB records (matching the new local YAML files)
• Cleans up verifier.py imports (removes unused requests, fixes pathlib placement)

Context

The hoagie data update (#514) switched the verifier to local YAML files with updated requirement category names (e.g. "Theory" → "Theoretical Computer Science", "Systems" → "Computer Systems"). Users who had manually settled courses to requirements have those old category names stored in their user_schedule JSON settled arrays. The verifier's _mark_settled function can no longer match these stale paths to the new requirement tree.

Impact: 7,381 out of 8,953 user profiles have stale settled paths.

Fix: The management command clears all settled arrays. The verifier's auto-settle feature will re-assign courses that can only satisfy one requirement. Users only need to manually re-settle ambiguous courses.

Deploy steps

After merging:

# Dry-run first
docker compose -f docker-compose.prod.yml exec -T web python manage.py clear_settled_paths

# Apply
docker compose -f docker-compose.prod.yml exec -T web python manage.py clear_settled_paths --apply

Test plan

• Verify management command dry-run shows expected numbers
• Verify --apply clears settled paths and creates POR/SPA Major records
• Verify verifier still works for existing majors (COS-BSE, ECO, etc.)
• Verify users with FIT/SPO majors still see requirements (their YAML files still exist)

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