Add typed Binance L2 capture source

[tradingexpert]

Summary

• add exact, typed Binance L2 depth, aggregate-trade, and book-ticker records
• stream completed gzip captures without loading multi-day datasets into memory
• validate REST snapshot bridging and pu/u continuity per connection
• keep the source explicitly outside the canonical MBO DataSource and Replay boundary
• align architecture, connector, schema, data-guide, agent, and changelog documentation

Fidelity boundary

This PR does not convert Binance L2 into exchange-native L3 and does not feed Binance captures directly to Replay. It creates the validated input boundary for a later, named virtual-L3 reconstruction model.

Verification

• python -m ruff check .
• python -m pytest --cov=ordersim --cov-report=term-missing
  • 199 passed
  • 98.78% total coverage
  • 100% coverage for every Binance module
• parsed the first completed real BTCUSDT/ETHUSDT capture segment with no sequence failure
• python -m build
• python -m twine check <sdist> <wheel>
• installed the built native wheel in a fresh virtual environment and imported both the Binance source and C++ extension