Refactor export orchestration
Add ExportResult for structured export outcomes and refactor all five export helpers to accept an optional shared session while returning result data.
Rewrite sol export main() to orchestrate full exports in dependency order (segments, imports, entities, facets, config), isolate per-area failures, and print a unified summary.
Add end-to-end integration coverage for the export-to-ingest pipeline, including idempotence, per-area exports, staging behavior, dry-run handling, and orchestrator error resilience.