Task: Resolve codegen feature gaps blocking the remaining trading instrument conversions

Convert the 7 remaining hand-crafted trading instrument sub-types (bond, commodity, credit, scripted, composite, fra, swap legs) to codegen by first closing the three codegen feature gaps that block them, each discovered and documented in the conversion task's notes:

(a) Nested domain groups: the domain template supports only the fixed instrument_identity + audit_record groups and flat columns, so the C1202-nested domains of bond_instrument (bond_terms=/=bond_features=/=bond_option, several members non-persisted) and the similarly-nested commodity_instrument=/ =credit_instrument cannot regenerate zero-diff – a generated flat domain would break every consumer of the nested sub-structs (persistence, ores.ore XML round-trip mappers, Qt forms).

(b) Column-name-to-group-field mapping: the mapper template emits r.identity.{{column_name}} keyed on the model column name while the ores.trading.instrument_identity field-group hardcodes the instrument_id field name, so scripted_instrument's PK column id cannot map into the group (its hand-crafted mapper bridges by hand: r.identity.instrument_id = v.id). The alternatives – renaming the DB column or dropping the identity group – both break zero-diff.

(c) Service paste-block/custom methods: the service template has no paste-block/custom-method extension mechanism, so composite_instrument=/=fra_instrument and the swap-leg entities' custom transactional service logic (save_*_instrument(data, legs), remove_*_instrument, get_legs=/=get_legs_batch) cannot be reproduced by generation.

Then convert each entity following the proven pattern: modern-format model bound to the trading-instrument variability profile, zero-diff regeneration across all facets (verified with a second pass), NATS eventing-integration-test facet enabled, messaging path reconciled, CMake synced, build + tests green.

• The codegen domain template supports arbitrary nested domain groups beyond the fixed identity/audit groups, including non-persisted members, so bond_instrument=/=commodity_instrument/ credit_instrument regenerate zero-diff.
• The codegen mapper supports mapping a model column name to a different identity-group field name, so scripted_instrument's id PK column regenerates zero-diff.
• The codegen service template supports paste-block/custom-method extension points reproducing the composite/fra/swap-leg transactional service logic.
• All 7 entities (bond, commodity, credit, scripted, composite, fra, swap legs) converted per the established pattern: profile-bound model, eventing facet enabled, messaging reconciled, second-pass zero-diff verified.
• Build green and ores.trading.{api,core,service}.tests plus consumer libs green after each batch.

Deferred from the conversion task on 2026-08-09: all four remaining flat-or-nested candidates (bond, commodity, credit, scripted) are feature-gated, not effort-gated; composite/fra/swap-legs were already deferred there for the same class of reason. The task is the follow-up those deferral notes point at.

Manual QA scenarios (scaffolded via compass add test_scenario, run through the QA Validation Runner panel) that verify this task. Link new ones here as they're created; the scenario doc itself links back via its "Verifies task" field.