refactor(global): move config to global package and consolidate handlers

- Move Config struct and related functions to global package
- Consolidate handler utilities into utils package
- Remove deprecated handlers and instance packages
- Add new handlers package with settings and proxy functionality
- Update config.json to include watchdog enabled flag

handlers/settings.go

@@ -0,0 +1,18 @@
+package handlers
+
+import (
+	"fmt"
+	"net/http"
+
+	"super-frpc/postLog"
+	"super-frpc/utils"
+)
+
+func GetSettingsHandler(w http.ResponseWriter, r *http.Request) {
+	_, err := utils.Auth(w, r, http.MethodGet, "superuser", "admin")
+	if err != nil {
+		utils.SendErrorResponse(w, http.StatusUnauthorized, err.Error())
+		postLog.Warning(fmt.Sprintf("[GetSettingsHandler] Auth failed: %v", err))
+		return
+	}
+}