- Replace manual spread-fee calc with netProfit() call — matches
scanner's exact fee model (round-trip 0.07%)
- Each direction gets correct buy/sell fee pairing
- Add PeakNet field to record true max during window, not close-time value
- Log peak net with +/- sign instead of approx symbol
- New SpreadWindowTracker in types.go watches BG↔HL spread for all
tracked coins, both directions
- Logs duration when spread stays above trade threshold then converges
- Wired into main loop after each scan tick
- Filters sub-100ms windows as noise