Precompile replay event stream once

[tradingexpert]

Summary

• compile Replay's immutable MBO event stream into primitive columns once at construction
• pass the read-only compiled view into each ReplayGateway created by run/run_many
• document why this matters for future boundary-batched replay

Tests

• python -m ruff check .
• python -m pytest
• mkdir -p build/cpp && c++ -std=c++17 -Wall -Wextra -pedantic -Icpp cpp/tests/matching_engine_core_test.cpp -o build/cpp/matching_engine_core_test && build/cpp/matching_engine_core_test

Coverage: 98.18% total.