cyi-box: Memphis-style toolbox admin platform

Go(fun)+SQLite backend, Vue 3 frontend. Modules: dashboard, pay gateway
(Epay-compatible + CDK stock), license/card system (per-app appid, domain
binding), AI memory bank with built-in MCP server (/mcp, FTS5 search,
signed read links), server SSH monitor + terminal + SFTP, proxy pool with
protocol-level alive checks, DB manager (mysql/pg/sqlite + SQL
autocomplete + import/export), disk share, vault (AES-GCM + TOTP),
bookmarks, dev tools.

Generated with [Devin](https://devin.ai)

Co-Authored-By: Devin <158243242+devin-ai-integration[bot]@users.noreply.github.com>

backend/internal/service/setting.go

@@ -0,0 +1,39 @@
+package service
+
+import (
+	"strings"
+
+	"github.com/cyi-cc/fun"
+
+	"github.com/cyi-cc/cyi-box/backend/internal/dto"
+	"github.com/cyi-cc/cyi-box/backend/internal/store"
+)
+
+// SettingSvc 站点级 KV 设置：读取对所有登录用户开放，写入仅管理员
+type SettingSvc struct {
+	fun.Ctx
+	Store *store.Store
+}
+
+func (s *SettingSvc) Get(d dto.SettingDto) (dto.SettingView, error) {
+	key := strings.TrimSpace(d.Key)
+	if key == "" || len(key) > 64 {
+		return dto.SettingView{}, fun.Error(4001, "key 必填且不超过 64 字符")
+	}
+	v, err := s.Store.GetSetting(key)
+	if err != nil {
+		return dto.SettingView{}, err
+	}
+	return dto.SettingView{Value: v}, nil
+}
+
+func (s *SettingSvc) Set(d dto.SettingDto) (dto.OkView, error) {
+	key := strings.TrimSpace(d.Key)
+	if key == "" || len(key) > 64 || len(d.Value) > 2000 {
+		return dto.OkView{}, fun.Error(4001, "key 必填且不超过 64 字符，value 不超过 2000 字符")
+	}
+	if err := s.Store.SetSetting(key, strings.TrimSpace(d.Value)); err != nil {
+		return dto.OkView{}, err
+	}
+	return dto.OkView{Message: "已保存"}, nil
+}