debug: add WriteDebugLog inside iframe to confirm calendar-data delivery + log.Printf to WriteDebugLog

cmd/verstak-gui/bindings_debug.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"log"
 	"os"
 	"path/filepath"
 	"time"
@@ -13,6 +14,7 @@ func (a *App) WriteDebugLog(msg string) {
 	if !a.IsReady() {
 		return
 	}
+	log.Printf("[js] %s", msg)
 	logPath := filepath.Join(a.vault, ".verstak", "debug.log")
 	line := fmt.Sprintf("[%s] %s\n", time.Now().Format("2006-01-02T15:04:05"), msg)
 	f, err := os.OpenFile(logPath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0o644)