Task: Move the rates family's shared children onto the bond shapes

The cap/floor strikes and schedules and the swaption's option block sit on the shapes the bond pilot built, with their registration in the root that owns them and their text-typed dates and collections retyped.

• The cap/floor strikes are rows of instrument_strikes and its schedules are rows of instrument_schedules and instrument_schedule_dates, written by the import and read by the export.
• The swaption's option data is rows of instrument_options and its four children, with premium_amount, premium_currency, premium_pay_date, exercise_prices and settlement_fixing_date typed rather than text, and instrument_option_exercise_fees.start_date typed as a date.
• The rates header's Delete cascade names the shared children, so a header delete closes them.
• instrument_schedules.owner_role's check lists the rates family's owner roles beside trs_funding, repo, ascot_swap, option and trs.
• The children's registration sits in the root that owns them, not in registrar_bond.cpp.
• The ORE round trip keeps a cap/floor's strikes and schedules and a swaption's option block.

Stage 1, merged as PR #2986, is the family's ownership of the children: the header's cascade, the catalogue's child arrays, and the schedule owner role.

1. The shapes. The bond pilot's instrument_strike, instrument_schedule, instrument_schedule_date, instrument_option and its keyed children are the target. The family writes to them; it does not widen them.
2. The retyping, finding R5, decided. ORE states PremiumAmount, PremiumPayDate, ExercisePrices and the option premiums' SettlementFixingDate as xs:string, and the schema copied the string. The storage is typed and the boundary converts, as the family's end_date does: premium_amount becomes numeric(28, 10), premium_pay_date and both settlement_fixing_date columns become date.
3. exercise_prices, the fourth child. The column holds a list in a string and the option block has three keyed children where the design's entity table names four. instrument_option_exercise_price is the fourth: the trade, the ordinal, the exercise date and the price, as instrument_option_premium is keyed. The text column is dropped. premium_currency stays text, because a currency code is text in every other table here and soft-FKs to ores_refdata_currencies_tbl.
4. The registration root, finding R11. Move the shared children's registration out of registrar_bond.cpp into the root that owns them.
5. The mapper. swap_instrument_data gains one vector per child; forward_capfloor fills the strikes and the schedules, forward_swaption fills the option block, and the reverse mappers read them back. The import handler calls the save_strike, save_schedule and save_option_block helpers the bond path already has, with owner_role swap for a leg's schedule and option for the exercise dates.
6. The export. The export service reads the child tables for the rates trade ids into the batch arrays and as_swap gathers them by trade id.
7. The proof. A cap/floor round trip that keeps its strikes and schedules, and a swaption round trip that keeps its option block.
8. Order. The cap/floor first, end to end, with a build and the round trip between it and the swaption.

Every number this task claims about a tree, with the command that produced it and the commit it was measured at. A number without both is not a measurement, because a clean-up record describes a tree and trunk moves under a branch: a consumer count, a gate's component count and a suite's size all change with no code changing, and the reader of a bare number cannot tell which tree it came from. Where the raw output matters, put it in an evidence/ file beside the task and name that file in the Command column.

• Unit 4 must land before the corpus round trip of unit 8: a cap/floor's strikes and schedules are not stored at all today, and the option block's dates are text, so the trip cannot be lossless until they are.
• It must also land before the composite key of unit 5, so the key is added once, to tables that are final.

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

The rates family writes the shared children the bond pilot built, and they survive the round trip. The cap/floor states its strikes as instrument_strikes rows and its underlying swap's schedule as instrument_schedules and instrument_schedule_dates rows; the swaption states its option block as instrument_options and four keyed children, including instrument_option_exercise_price, the fourth child the design's entity table names and the models never had. The option block's text dates and its price list are typed: premium_amount is a decimal, premium_pay_date and both settlement_fixing_date columns are dates, and exercise_prices is the child rather than a string. The header's cascade names all eight children, and their registration sits in registrar_rates.cpp rather than the bond family's root (finding R11).

Three residuals, all deliberate:

• The database-level end-to-end proof is unit 8's. The acceptance's "written by the import and read by the export" is proved by the mapper round trips and by the wiring compiling, not by importing a rates trade into the database and exporting it. The corpus round trip at the new shape is already the task Prove the rates round trip over the corpus, which is where that proof belongs, and duplicating it here would prove it twice.
• Bonds now carry their exercise prices through the fourth child. The instrument_option shape is shared with the bond family, so retyping the option block and dropping exercise_prices would have silently dropped bond prices; the bond writer and reader convert at the boundary and write and read the child instead. This is a behaviour change for the bond family and is called out in the PR. The price list pairs token i with exercise date i, so a document stating more prices than dates loses the tail.
• split_numbers is duplicated in the ORE mapper and the import handler, in two components' anonymous namespaces. Not worth a shared API yet.

An earlier attempt at this unit bundled a cherry-pick of a trunk hotfix and two merge commits; both are gone, and the branch is three commits on ceced2447a with a clean history. The first database recreate failed because the branch's base predated the trunk seed hotfix, which is what rebasing onto current trunk fixed; no trunk fix is carried in this unit.