refactor: rename validation/ domain to enrichment/

[rorybyrne]

Context

The validation/ domain currently owns hook execution types and services (HookRunner, HookResult, HookStatus, HookInputs, HookRecord, BatchRecordOutcome, ValidationService). Both the deposition and ingest pathways depend on these types.

The name "validation" implies deposition-specific, but the domain is really about enrichment — running hooks against records, producing features, handling retry logic. Both pathways use it.

What

Rename domain/validation/ to domain/enrichment/. Update all imports, events, DI providers, and tests.

Key renames:

• ValidationService → EnrichmentService (or keep as-is internally)
• ValidationRun → EnrichmentRun (or HookRun)
• ValidateDeposition handler → EnrichDeposition
• ValidationCompleted / ValidationFailed events → EnrichmentCompleted / EnrichmentFailed
• All import paths: osa.domain.validation.* → osa.domain.enrichment.*

Why

• "Validation" misleadingly implies the domain is deposition-specific
• "Enrichment" captures the full purpose: running hooks, producing features, retry on OOM
• The ingest domain already imports hook types from validation — the cross-domain dependency is architecturally correct (ingest → enrichment), but the naming obscures this

Depends on

• feat: add harvest domain for bulk ingestion pipeline #104 (OOM retry feature — so HookService exists when we rename)

Effort

M — mechanical refactor, no logic changes. (human: ~1 day / CC: ~15 min)

[rorybyrne]

Additional scope from eng review (#105-oom-retry)

During the OOM retry eng review, we identified that the handler restructuring should happen during this rename:

1. Move RunHooks handler from ingest/handler/run_hooks.py to enrichment/handler/ — both hook-execution handlers should live in the enrichment domain (consistency with ValidateDeposition → EnrichDeposition)

2. Enrich IngesterBatchReady event with hooks: list[HookDefinition] and convention_srn — so the handler doesn't need IngestRunRepository to look up the convention (same pattern as DepositionSubmittedEvent which carries everything the handler needs)

This eliminates the cross-domain import where RunHooks (in enrichment/) would otherwise need to import from ingest/ repository.