Adopt live maker inventory and add position reconciliation

[wjllance]

Summary

• Adopt the venue’s starting position at maker startup and baseline live PnL from the current mark.
• Scope live order IDs to the current run so fills, reconnect validation, and exit orders are attributed deterministically.
• Reconcile observed venue position against current-run fills, with an immediate fail-safe on unexplained drift.
• Emit richer fill metadata in maker output and add coverage for reconciliation and scoped client order IDs.

Testing

• Added unit tests for current-run fill deduplication, session boundary validation, scoped order IDs, and immediate reconciliation exits.
• Updated reconnect snapshot tests to use the new run-order prefix.
• Not run (not requested).