feat: 添加联系我们配置接口和字典配置缓存

1. 新增DictionaryItem字典配置结构体
2. 添加字典配置缓存及失效逻辑
3. 实现联系我们接口的业务逻辑和测试用例
4. 注册联系我们API路由
5. 集成字典配置到admin内部客户端
6. 处理字典配置更新的kafka事件

server/im_http.go

@@ -1514,6 +1514,39 @@ func serveIMAbuseReports(wrt http.ResponseWriter, req *http.Request) {
 	writeIMSuccess(wrt, req, abuseReportPayload(report))
 }
 
+// imContactUsDictType is the admin dictionary type backing the mobile
+// "contact us" entries.
+const imContactUsDictType = "im_contact_us"
+
+func serveIMContactUs(wrt http.ResponseWriter, req *http.Request) {
+	if req.Method != http.MethodGet {
+		writeIMError(wrt, req, http.StatusMethodNotAllowed, 30002, imReasonMethodNotAllowed, "method not allowed", nil)
+		return
+	}
+	if _, ok := authenticateIMHTTPBearer(wrt, req); !ok {
+		return
+	}
+	items, err := store.DictionaryConfig.Get(imContactUsDictType)
+	if err != nil {
+		if errors.Is(err, types.ErrUnsupported) || errors.Is(err, types.ErrNotFound) {
+			items = nil
+		} else {
+			writeIMError(wrt, req, http.StatusInternalServerError, 90000, imReasonInternal, "internal error", nil)
+			return
+		}
+	}
+	payload := make([]map[string]any, 0, len(items))
+	for _, item := range items {
+		label := strings.TrimSpace(item.Label)
+		value := strings.TrimSpace(item.Value)
+		if label == "" || value == "" {
+			continue
+		}
+		payload = append(payload, map[string]any{"label": label, "value": value})
+	}
+	writeIMSuccess(wrt, req, map[string]any{"items": payload})
+}
+
 func serveIMFeedbackConfig(wrt http.ResponseWriter, req *http.Request) {
 	if req.Method != http.MethodGet {
 		writeIMError(wrt, req, http.StatusMethodNotAllowed, 30002, imReasonMethodNotAllowed, "method not allowed", nil)