orders: route adaptive, algo and what-if through the shared encoder (ibx#318)

[userFRM]

Stacked on #246 — review the tip commit only.

Problem

build_order_request computes the extended-attribute block partway down, and three order types returned before reaching it. Their request variants carried no attribute block at all, so Order::attrs() was never consulted on those paths and their encoders emitted none of it.

Setting outsideRth on an adaptive, algo or what-if order was accepted by the API and silently ignored — the order went out regular-hours-only with nothing reporting the difference. The same early return bypassed the parent link and the OCA group, so an adaptive or algo order used as a bracket child was submitted unlinked and outside its group, which is what the attribute block exists to prevent. The time-in-force was hard-coded to DAY on all three.

What this changes

Patching the missing tags into each dedicated encoder would leave the rest of the block — hidden, display size, minimum quantity, good-after, GTD expiry, discretionary amount, sweep-to-fill, all-or-none, trigger method, cash quantity, conditions — still dropped on those paths, and would put the emission in four places.

These route instead, the way the adjustable stop does in #246: Adaptive, Algo and WhatIf are OrderKind variants carried by SubmitEx, and the three standalone encoder arms are gone.

Their own tags keep their values and their position — after tag 204 and the attribute block, where the encoders this replaces put them: 18=e and the adaptive priority parameter, the algo strategy with 849 and its parameter pairs, and the what-if flag. A what-if is still tracked under its marker so the response is recognised as a preview.

Breaking change to the low-level Rust API

Pre-1.0, and the same shape #246 already applied to the adjustable stop:

• OrderRequest::SubmitAdaptive, SubmitAlgo and SubmitWhatIf are removed — use SubmitEx { kind: OrderKind::Adaptive | Algo | WhatIf, tif, attrs }.
• Context::submit_adaptive, submit_algo and submit_what_if take a time-in-force and an OrderAttrs, as submit_adjustable_stop does.
• OrderKind is no longer Copy, because the algo parameters it now carries own their strings.

The Client/EClient and Python surfaces are unchanged.

Tests

• the_algo_order_types_carry_the_attributes_the_caller_set — at the API boundary, where the drop happened: all three types, outside-RTH, parent link, OCA group and a non-DAY tif.
• adaptive_wire_carries_the_attributes_and_keeps_its_algo_tags
• algo_wire_carries_the_attributes_and_keeps_its_algo_tags
• what_if_wire_carries_the_attributes_and_keeps_its_preview_flag

The three wire tests assert on the bytes, because the enum-level tests passed throughout the period the children shipped naked. Each fails by name against a compiling reversion of the production change it covers.

Closes #318.

Test plan

• Mutation: dropping the caller's attributes and tif on each of the three routing arms fails the_algo_order_types_carry_the_attributes_the_caller_set by name.
• Mutation: dropping the what-if flag fails what_if_wire_carries_the_attributes_and_keeps_its_preview_flag.
• Mutation: dropping 18=e fails adaptive_wire_carries_the_attributes_and_keeps_its_algo_tags.
• The three wire tests assert on the bytes, because the enum-level tests passed throughout the period the children shipped naked.
• Wire output verified byte-identical to the standalone encoders — including field order, body length and checksum — for adaptive, what-if and all six algo strategies with default attributes.
• cargo check --offline clean on --lib, --lib --features python, --bins, --examples, and each integration target individually.
• tests/ib_paper_compat compared against a clean checkout of the base commit — identical sorted diagnostic sets.
• cargo test --offline --lib — only the two known config::expiry_tests failures, which fail on the base commit for missing legacy tzdata (fixed separately in config: resolve the legacy timezone names IB states its times in (ibx#335) #336).

[userFRM]

Closing this. It's in #409 along with the rest of the fork, which is easier to take in one piece than sixty separate branches.