feat: Add call duration to call detail view

internal/tui/model.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"time"
 
 	"telephony-inspector/internal/capture"
 	"telephony-inspector/internal/config"
@@ -713,6 +714,11 @@ func (m Model) renderCallDetail() string {
 	b.WriteString(fmt.Sprintf("From: %s\n", flow.From))
 	b.WriteString(fmt.Sprintf("To: %s\n", flow.To))
 	b.WriteString(fmt.Sprintf("State: %s\n", flow.State))
+
+	// Calculate and display duration
+	duration := flow.EndTime.Sub(flow.StartTime)
+	b.WriteString(fmt.Sprintf("Duration: %s\n", duration.Round(time.Millisecond)))
+
 	b.WriteString(fmt.Sprintf("Packets: %d\n\n", len(flow.Packets)))
 
 	// Network Summary Section