Refactor code structure for improved readability and maintainability; optimize performance in key functions.

docs/modules/policy/evidence-hooks.md

@@ -173,6 +173,11 @@ validationSchema: "https://stellaops.io/schemas/evidence/feature-flag/v1"
 | `Expired` | Evidence older than maxAge |
 | `InsufficientTrust` | Source trust score too low |
 
+## Persistence
+
+- Hook registry: `policy.evidence_hooks` with `max_age_seconds` and `min_trust_score`.
+- Evidence submissions: `policy.submitted_evidence` with `validation_status`, `reference`, and optional `dsse_envelope`.
+
 ## Submission Flow
 
 ```