Task 8 evidence: unmatched local sections are returned for UI review.

Command run:
ddev exec php artisan test --filter=CcliTranslationPairingServiceTest

Relevant passing test:
✓ returns unmatched_labels for sections not in CCLI

Observed assertions in tests/Feature/CcliTranslationPairingServiceTest.php:
- Local arrangement contains Verse 1, Chorus, Bridge.
- CCLI paste contains Verse 1 and Chorus only.
- result['unmatched_labels'] contains "Bridge".
- mapping still has all three local labels.
- Bridge mapping has ccli_label = null and empty distributed line placeholders.

Full targeted result:
Tests: 5 passed (20 assertions)
Duration: 0.46s