chore: harden knowledge graph storage and clear common clippy warnings

Enforce stable 1:1 entity embeddings, relationship endpoint auth, and
user-scoped deletes; align schemas/migrations and resolve common crate
clippy findings.

evaluations/src/corpus/store.rs

@@ -308,6 +308,7 @@ fn build_manifest_batches(manifest: &CorpusManifest) -> Result<ManifestBatches>
                 entities.push(entity.clone());
                 entity_embeddings.push(KnowledgeEntityEmbedding::new(
                     &entity.id,
+                    entity.source_id.clone(),
                     embedded_entity.embedding.clone(),
                     entity.user_id.clone(),
                 ));