[TexasCoding]

Closes #553

Maps the 10 new core RFQ batch endpoints flagged by Spec Drift Detection run 39767253047 onto a new client.communications.rfq_batches sub-resource, in both sync and async versions:

• list / list_all / get / create / delete / accept / best_quotes
• quotes.list / quotes.create / quotes.delete / quotes.confirm

Request bodies are extra="forbid" models. Prices are DollarDecimal and go on the wire as _dollars. POST/PUT/DELETE use the existing non-retrying transport helpers. Endpoints are registered in METHOD_ENDPOINT_MAP and BODY_MODEL_MAP. Specs were re-synced: core now has 128 operations, 127 of them mapped. Version is 22.3.0 (minor, additive).

Blast radius (written by hand; GitNexus is unavailable)

• New code: RFQ batch models in kalshi/models/communications.py, the rfq_batches sub-resources in kalshi/resources/communications.py, and their exports. No existing method signatures changed.
• Modified: QuoteExecutedPayload (WS) gains an optional rfq_batch_id. Existing payloads still parse.
• Tests and contracts: new map entries, new tests, and an extra-policy list update. The Retry-After HTTP-date fixture in tests/test_async_client.py moved to 2030 because its 2026-10-21 date is now in the past.
• Specs: openapi, asyncapi and perps SCM re-vendored. The other new fields are optional and left unmapped (follow-ups).
• Risk: low.

Gates

• ruff: pass
• mypy: pass
• unit tests: 4926 passed, 3 skipped
• strict contract tests: 901 passed