feat: separate realtime display prices from strategy candles

[pjy008008]

Summary

• Stream Alpaca SIP trades through a 250 ms display coalescer into Redis latest-price state and Pub/Sub.
• Poll finalized Alpaca 30-minute bars and aggregate only the strategy cadences: 30m, 1h, 4h, and 1d.
• Keep display-price traffic separate from the durable evaluation stream.
• Include interval OHLCV in display updates so the browser can build 1m, 5m, and 15m chart bars.
• Make the worker consume one evaluation-ready event containing the actual finalized strategy candles.

Architecture boundary

1m/5m/15m data is display-only and cannot trigger strategy evaluation. Strategy evaluation remains fixed to finalized 30m/1h/4h/1d candles. Legacy 1m strategy plans are mapped to the existing 30m cadence for compatibility.

Verification

• ./gradlew.bat test
• Production-source audit for small-timeframe strategy events
• git diff --check