Abstract provider market catalogs

[luisleo526]

Summary

• add provider-neutral asset class, market type, listing, query, and derivative contract models
• resolve exact CCXT unified markets and normalize venue IDs, base/quote/settle assets, contract size, linear/inverse terms, expiry, strike, and option type
• add a provider registry with Python entry-point discovery so broker adapters do not require CLI branching
• make the backtest CLI provider-neutral while retaining --exchange as an alias for --venue
• record resolved market metadata in backtest provenance
• make provider implementations in pineforge-data Python-only and remove the C++ provider placeholder
• document the provider contract and contribution path for future broker PRs

Why

The initial harness selected CCXT directly and represented only a symbol plus exchange. That cannot safely distinguish spot, swaps, futures, and options or support community broker adapters without adding provider-specific branches. Exact catalog resolution also avoids deriving contract semantics from symbol text.

User and developer impact

Existing CCXT users can continue using --exchange; new integrations can register a MarketDataProvider factory and use the same CLI through --provider and --venue. Backtest reports now include the exact resolved listing and contract provenance.

Validation

• ruff format --check src tests
• ruff check .
• mypy src
• pytest (44 passed, 1 skipped)
• python -m build (sdist and wheel)
• live Kraken catalog resolution for BTC/USD
• PINEFORGE_DOCKER_TEST=1 pytest tests/test_docker_integration.py (1 passed)