Reconcile OpenAPI 3.29.0 spec drift (v14.0.0)

[TexasCoding]

Closes #510. Closes #511.

Reconciles nightly spec-drift against upstream OpenAPI 3.29.0 content (same info.version, paths 95 → 96) plus matching perps/Klear/AsyncAPI updates. Ships as v14.0.0 because perps WS MarginFillPayload and MarginUserOrderPayload gained a required order_source (same constructor-breaking precedent as v13.0.0).

Breaking

• MarginFillPayload.order_source and MarginUserOrderPayload.order_source (Literal["user", "system"], required). system marks liquidations and margin exit / trailing-stop triggers. Live stream callers are unaffected. Tests/mocks that construct these payloads must pass the source (typically "user").

Added

• live_data.weather_calibrations(city) — published weather-index configuration timeline.
• Optional WeatherIndexPoint.receipt_basis.
• api_keys.list(*, fcm_subtrader_id) and optional fcm_subtrader_id on create() / generate() / ApiKey (mutually exclusive with subaccount). Optional warning on create/generate responses.
• portfolio.set_target_balance_allocation(..., resting_margin_reservation=) (max / sum).
• fcm.orders / orders_all: subtrader_id optional when client_order_ids is supplied (max 100).
• Optional subaccount on historical.positions() / positions_all().
• Perps margin.fee_tier_rates().
• Optional MarginMarket.asset_class.
• Klear FCM margin API keys (list_fcm_api_keys / create_fcm_api_key / generate_fcm_api_key / delete_fcm_api_key).
• Klear member_funding_payments() / member_funding_payments_all().
• Klear estimate_maintenance_margin(..., date=, clearing_type=) plus optional breakdown fields.
• WS subscribe_cfbenchmarks_value_5hz().

Changed (non-breaking)

• Event.available_on_brokers is optional. The spec dropped the field; constructors that pass it still work.

Spec notes

• Core OpenAPI 3.29.0: 109 operations / 108 mapped. Still unimplemented on the core client: POST /portfolio/intra_exchange_instance_transfer.
• Perps OpenAPI: 47 → 48 operations.
• Perps SCM: 19 → 24 operations. Still unimplemented: GET /margin/large_trader_positions.
• AsyncAPI 14 → 15 channels (cfbenchmarks_value_5hz). 12 typed subscribe_* helpers.

Verification

• uv run ruff check . — clean
• uv run mypy kalshi/ — clean
• uv run pytest tests/ -m "not integration" --ignore=tests/integration — 4414 passed, 3 skipped