fix: use fresh scan state in trading snapshot

fix: use fresh scan state and start US worker on HF

fix: re-run nightly scan when prior completion is older than SCAN_MAX_AGE_HOURS (default 20h)

feat: add /api/supabase-ping keep-alive endpoint (DB + Storage)

Restore latest known BIST scan snapshot

Sync scan state before status reads

Skip stale boot scans and preserve completed scan timestamps

Prevent duplicate completed scan notifications

Add Alpaca broker integration

Harden Telegram menu webhook