Replay runner MVP: recordable market data, replay-sim, and comparable receipts

[phenomenoner]

Why

The product promise is replay-first. That only becomes real when market data can be recorded/replayed and the engine supports bounded non-live execution modes.

Scope

• define concrete event source and receipt artifacts for replay runs
• build a minimal replay-sim runner that consumes recorded/normalized market events
• define a parallel live-sim path that uses live market data without submitting live orders
• keep replay/live-sim receipts comparable enough for review

Acceptance criteria

• replay-sim can process a recorded event stream into intent/risk/execution receipts
• live-sim and replay-sim share the same core contract vocabulary where feasible
• event source identity and feature/synthesizer versions are included in run receipts
• no documentation implies production live readiness