feat(userMgr): add user removal functionality

- Implement RemoveUser function in database.go to delete users
- Add RemoveUserHandler to handle HTTP requests for user removal
- Update API documentation with new /userMgr/remove endpoint
- Add route for user removal in router.go

userAct.go

@@ -24,6 +24,10 @@ type CreateUserRequest struct {
 	Type     string `json:"type"`
 }
 
+type RemoveUserRequest struct {
+	TargetUserID int `json:"targetUserID"`
+}
+
 func RegisterHandler(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {
 		SendErrorResponse(w, http.StatusMethodNotAllowed, "Invalid request method")
@@ -270,4 +274,60 @@ func CreateUserHandler(w http.ResponseWriter, r *http.Request) {
 		"username": user.Username,
 		"type":     user.Type,
 	})
+}
+
+func RemoveUserHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		SendErrorResponse(w, http.StatusMethodNotAllowed, "Invalid request method")
+		postLog.Warning(fmt.Sprintf("[RemoveUserHandler] Invalid request method: %s", r.Method))
+		return
+	}
+
+	if !ValidateTimeStamp(r.Header) {
+		SendErrorResponse(w, http.StatusBadRequest, "Invalid or missing X-Timestamp in header")
+		return
+	}
+	userID, err := extractUserIDFromToken(r.Header.Get("X-Token"))
+	if err != nil {
+		SendErrorResponse(w, http.StatusUnauthorized, "Invalid or missing token")
+		postLog.Warning(fmt.Sprintf("[RemoveUserHandler] Invalid or missing token: %v", err))
+		return
+	}
+	user, err := GetUserByID(userID)
+	if err != nil {
+		SendErrorResponse(w, http.StatusInternalServerError, "Failed to get user info")
+		postLog.Error(fmt.Sprintf("[RemoveUserHandler] Failed to get user info for user [%d]%s: %v", userID, GetUsernameByID(userID), err))
+		return
+	}
+	if user.Type != "superuser" {
+		SendErrorResponse(w, http.StatusForbidden, "Permission denied")
+		postLog.Warning(fmt.Sprintf("[RemoveUserHandler] Permission denied: non-superuser token for user [%d]%s", userID, GetUsernameByID(userID)))
+		return
+	}
+	
+	body, err := io.ReadAll(r.Body)
+	if err != nil {
+		SendErrorResponse(w, http.StatusBadRequest, "Failed to read request body")
+		postLog.Warning(fmt.Sprintf("[RemoveUserHandler] Failed to read request body: %v", err))
+		return
+	}
+	defer r.Body.Close()
+
+	var req RemoveUserRequest
+	if err := json.Unmarshal(body, &req); err != nil {
+		SendErrorResponse(w, http.StatusBadRequest, "Invalid request format")
+		postLog.Warning(fmt.Sprintf("[RemoveUserHandler] Invalid request format: %v", err))
+		return
+	}
+	if req.TargetUserID == 0 {
+		SendErrorResponse(w, http.StatusBadRequest, "TargetUserID is required")
+		postLog.Warning("[RemoveUserHandler] RemoveUser failed: TargetUserID is empty")
+		return
+	}
+	if err := RemoveUser(req.TargetUserID); err != nil {
+		SendErrorResponse(w, http.StatusInternalServerError, err.Error())
+		postLog.Error(fmt.Sprintf("[RemoveUserHandler] Failed to remove user [%d]: %v", req.TargetUserID, err))
+		return
+	}
+	SendSuccessResponse(w, "User removed successfully", nil)
 }