Wraps ENUM type creation in findings.ledger schema with DO blocks that catch
duplicate_object so migration 001 can re-run on a partially-provisioned DB
without crashing. Minor corrections to 002 and 005 (syntax alignment).
Updates RLS contract + operations docs to reflect the replay-safe semantics.
WebService + persistence csproj get the Infrastructure.Postgres migration
reference needed for StartupMigrationHost wiring.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>