Add comprehensive integration tests for plan §8 requirements:
- Document round-trip: 1000 docs indexed and retrieved, verified distributed across ≥2 nodes
- Search covers all shards: 100 docs with unique keywords, each search returns 1 hit
- Facet aggregation: 100 docs across 3 colors, facet counts sum to 100
- Offset/limit paging: 50 docs, 5 pages of 10 match single limit=50 query
- Settings broadcast: synonyms propagated to all 3 nodes
- Task polling: 500 doc batch, poll until succeeded
- Node failure with RF=2: marked #[ignore], requires docker-compose-dev-rf2.yml
All tests use docker-compose-dev stack (3 Meilisearch nodes + Miroir).
Closes: bf-45zni
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
