feat(client): add combo market catalog

[cesarenaldi]

Summary

• add RFQ REST routing and environment config for Combo market catalog requests
• expose list_combo_markets across sync/async public and secure clients
• add RFQ-owned Combo market models and pagination/request coverage

Verification

• uv run ruff check .
• uv run ruff format --check .
• uv run pyright
• uv run pytest -m "not integration"
• uv run pytest tests/integration/test_rfq_paginated.py -q

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Note

Low Risk
Additive public API and transport wiring; keyset pagination changes are backward-compatible defaults for existing gamma endpoints.

Overview
Adds RFQ REST support so clients can browse the Combo market catalog via a new keyset-paginated list_combo_markets API (optional exclude filter), wired through sync/async public and secure clients.

Introduces an rfq HTTP transport (environment.rfq_url), extends dispatch/context with service "rfq", and exports ComboMarket models that normalize binary yes/no outcomes from either structured or parallel outcomes / position_ids / outcome_prices wire shapes.

Keyset pagination is generalized with per-spec cursor_param (RFQ uses cursor instead of after_cursor) and optional max_page_size enforcement (100 for combo markets). Public exports and unit/integration tests cover models, specs, and live pagination.

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