Task: Verify currency SQL against evaluation checklist

Inspect refdata_currencies_create.sql against every criterion in the DB layer of the ores.refdata entity evaluation checklist. Record which criteria pass, which fail, and what must be added or corrected. Fix any gaps inline or file captures for deferred work.

• All DB-layer checklist criteria evaluated for: currency, rounding_type, monetary_nature, currency_market_tier.
• Standard audit columns confirmed for all four entities.
• GIST exclusion constraint and temporal pattern confirmed for all four.
• Natural key and version indexes confirmed for all four.
• Insert trigger and soft-delete rule confirmed for all four.
• Validation functions confirmed for all four.
• Any gaps fixed or filed as captures.
• Findings recorded in * Result section.
• Site builds cleanly.

All four DDL files verified against the DB-layer criteria in ores.refdata entity evaluation checklist. No gaps at the DB layer. One gap found at the codegen layer (see below).

The auxiliary types (rounding_type, monetary_nature, currency_market_tier) follow an identical structural pattern; currency is richer with entity-specific soft-FK validations in its insert trigger.

Codegen gap: All three auxiliary types have both <entity>_domain_entity.json and <entity>_entity.json in projects/ores.codegen/models/refdata/. Currency has only currency_entity.json — the currency_domain_entity.json is missing. The domain struct (currency.hpp) may be hand-crafted or generated from the entity model alone. This is a drift risk: if the DB schema evolves, the domain struct may not be updated via codegen. Filed as a gap in the checklist result; needs a dedicated capture or fix.