REST `CONTRACT_MAP` missing 42 SDK models — promote `test_contract_map_completeness` to hard-fail

[TexasCoding]

From the v2.2.0 spec-drift hardening (#157). The WS contract map is now exhaustive and test_contract_map_completeness hard-fails on the WS side. The REST side leaves 42 SDK response/request models unmapped, with the test warn-only.

This is the same regression class that hid Balance.balance_dollars for five review rounds in v2.1.0 — an unmapped model is invisible to drift checks, so additive spec changes slide through silently.

Unmapped models

Reproduce with pytest tests/test_contracts.py::TestSpecDrift::test_contract_map_completeness -W error::Warning.

• kalshi.models.markets (4): BidAskDistribution, Candlestick, OrderbookLevel, PriceDistribution
• kalshi.models.orders (19): AmendOrderRequest, AmendOrderV2Request, AmendOrderV2Response, BatchCancelOrdersRequest, BatchCancelOrdersRequestOrder, BatchCancelOrdersV2Request, BatchCancelOrdersV2RequestOrder, BatchCancelOrdersV2Response, BatchCancelOrdersV2ResponseEntry, BatchCreateOrdersRequest, BatchCreateOrdersV2Request, BatchCreateOrdersV2Response, BatchCreateOrdersV2ResponseEntry, CancelOrderV2Response, CreateOrderV2Request, CreateOrderV2Response, DecreaseOrderRequest, DecreaseOrderV2Request, DecreaseOrderV2Response
• kalshi.models.events (2): MarketMetadata, SettlementSource
• kalshi.models.exchange (4): DailySchedule, MaintenanceWindow, Schedule, WeeklySchedule
• kalshi.models.portfolio (4): Deposit, IndexedBalance, PositionsResponse, Withdrawal
• kalshi.models.series (3): EventCandlesticks, ForecastPercentilesPoint, PercentilePoint
• kalshi.models.multivariate (6): AssociatedEvent, CreateMarketInMultivariateEventCollectionRequest, CreateMarketResponse, LookupPoint, LookupTickersForMarketInMultivariateEventCollectionRequest, LookupTickersResponse

Work

1. Add a ContractEntry to kalshi/_contract_map.py for each model, with the matching spec_schema lookup name from specs/openapi.yaml.
2. The V2 orders family clusters around the *OrderV2* request/response pairs and is the largest sub-batch (~12 entries). Suitable for a self-contained first PR.
3. Once mapped, drift on these models flows through test_additive_drift and test_required_drift. test_additive_drift is hard-fail post-Harden response-side spec drift: promote additive warnings to hard-fail #157, so any new spec field surfaces immediately.
4. Promote test_contract_map_completeness from warnings.warn to pytest.fail so the next unmapped model fails CI.

Acceptance

• len(CONTRACT_MAP) increases from 49 to ~91 (final number depends on whether nested sub-models get folded into their parent entries).
• pytest tests/test_contracts.py -W error::Warning -k test_contract_map_completeness passes.
• The test body's warnings.warn(...) is replaced with pytest.fail(...).
• No regression in test_additive_drift (any new failures must be addressed before flipping the gate).

Related

• Roadmap entry: "Map remaining REST sub-models / V2 family / internal containers (~42 entries) into CONTRACT_MAP and promote test_contract_map_completeness (REST) to hard-fail."
• WS side completed in Harden response-side spec drift: promote additive warnings to hard-fail #157.