Infer quote overlay state in notifications

[Pigbibi]

Summary

• infer quote-overlay state from known signal snapshot source names
• show LongBridge candlestick snapshots as quote-overlay no instead of unknown
• keep explicit quote_overlay_used values authoritative

Verification

• PYTHONPATH=.:../QuantPlatformKit/src:../UsEquityStrategies/src ../QuantPlatformKit/.venv/bin/pytest tests/test_notifications.py -q
• PYTHONPATH=.:../QuantPlatformKit/src:../UsEquityStrategies/src ../QuantPlatformKit/.venv/bin/ruff check notifications/renderers.py tests/test_notifications.py
• git diff --check