fix: parse configured field arrays through PostgreSQL text

[artiphishle]

Closes #11.

Summary

• cast serialized configured-field parameters through PostgreSQL text before parsing them as jsonb
• apply the correction to both create and replace paths
• keep passing deterministic JSON strings instead of JavaScript arrays
• add regression assertions for the Bun-safe SQL casts
• include a patch changeset

Root cause

Bun SQL encodes the bound JavaScript string as a JSON string scalar when it is cast directly with $n::jsonb. jsonb_array_elements_text then fails with cannot extract elements from a scalar.

Using $n::text::jsonb makes PostgreSQL parse the serialized JSON array text explicitly.

Validation

A rollback-only Bun/PostgreSQL probe isolated the failure to the metadata insert after vault.create_secret succeeded. The changed SQL matches the successful form from that probe.