fix: HL size floor, random scan jitter 50-250ms

- GetHLSize: change rounding from Sprintf (round-to-nearest)
  to math.Floor (floor), consistent with GetBitgetSize
- Scan interval: fixed 200ms → random 50-250ms to avoid
  lock-step with HyperLiquid's ~200ms allMids push cycle
- README: update architecture diagram, trading logic, config note

main.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	"log"
+	"math/rand"
 	"os"
 	"os/signal"
 	"strings"
@@ -113,10 +114,16 @@ func main() {
 
 	// Main loop
 	lastHour := -1
-	scannerTick := time.NewTicker(time.Duration(cfg.ScanIntervalMs) * time.Millisecond)
+
+	// Random jitter 50-250ms to avoid lock-step with exchange push cycles
+	jitterMin, jitterMax := 50, 250
+	randInterval := func() time.Duration {
+		return time.Duration(jitterMin+rand.Intn(jitterMax-jitterMin+1)) * time.Millisecond
+	}
+	scannerTick := time.NewTimer(randInterval())
 	statusTick := time.NewTicker(30 * time.Second)
 
-	log.Printf("[Monitor] Scanner running every %dms", cfg.ScanIntervalMs)
+	log.Printf("[Monitor] Scanner running every %d-%dms (random jitter)", jitterMin, jitterMax)
 
 	runLoop := true
 	for runLoop {
@@ -202,6 +209,8 @@ func main() {
 				notifier.SendTradeSummary(positions, now.Format("2006-01-02 15:04"))
 				lastHour = hour
 			}
+
+			scannerTick.Reset(randInterval())
 		}
 	}