[codex] Add account info subscriber hub

[NewYaroslav]

Summary

• add components::IAccountInfoSubscriber and components::AccountInfoHub for fan-out from the platform on_account_info() callback
• document the account-info subscriber contract and keep broker-specific trading-condition streams out of this DTO path
• cover routing, replay, removal, callback binding, and add the test to Ubuntu Smoke

Checks

• cmake -S . -B build-codex
• cmake --build build-codex --target account_info_hub_test -- -j1
• build-codex/account_info_hub_test.exe --gtest_brief=1
• cmake --build build-codex --target market_data_subscription_contract_test -- -j1
• build-codex/market_data_subscription_contract_test.exe --gtest_brief=1
• git diff --check