calendar_rules insert trigger references calendars.id, which does not exist (calendars use code as PK)

ores_refdata_calendar_rules_insert_fn() (line ~96 of projects/ores.sql/create/refdata/refdata_calendar_rules_create.sql) does:

not exists (
    select 1 from ores_refdata_calendars_tbl
    where tenant_id = NEW.tenant_id
      and id = NEW.calendar_code
      and valid_to = ores_utility_infinity_timestamp_fn()
)

but ores_refdata_calendars_tbl's primary key is (tenant_id, code, valid_from, valid_to) – it has no id column at all (see refdata_calendars_create.sql:59). Any calendar_rule insert/update fails with column "id" does not exist.

Causes 4 test failures in ores.refdata.core.tests (service_calendar_materialisation_service_tests.cpp, e.g. regenerate_exception_overrides_rule_holiday_back_to_business_day), surfaced while running the full suite for an unrelated IR curve fix (task C80D94BB). Root-cause commit: 7351a89f7 "[refdata] Regenerate calendar_rule/calendar_type/calendar_date/business_day_convention_type against current templates" – the FK check should read code = NEW.calendar_code, not id = NEW.calendar_code.

• projects/ores.sql/create/refdata/refdata_calendar_rules_create.sql:96
• projects/ores.sql/create/refdata/refdata_calendars_create.sql:59 (the actual PK shape)
• projects/ores.refdata/core/tests/service_calendar_materialisation_service_tests.cpp
• Root-cause commit: 7351a89f7