新增 Web 浏览端(Go+Vue 报表系统)

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/backend/internal/store/util.go

@@ -0,0 +1,10 @@
+package store
+
+import "os"
+
+func ensureDir(dir string) error {
+	if _, err := os.Stat(dir); err == nil {
+		return nil
+	}
+	return os.MkdirAll(dir, 0o755)
+}