fix: unify handler response format in log, permission, webhook handlers

- log_handler.go: Fix GetMyLoginLogs/GetMyOperationLogs/GetLoginLogs/GetOperationLogs to use {code, message, data}
- permission_handler.go: Fix all error responses to use {code, message}
- webhook_handler.go: Add missing "message" field in success responses, wrap data in data object with list/total/page/page_size
- webhook_handler_test.go: Update test to match new response format

Standardize all JSON responses to {code: 0, message: "success", data: ...} for success
and {code: XXX, message: "..."} for errors.

internal/api/handler/webhook_handler.go

@@ -35,7 +35,7 @@ func (h *WebhookHandler) CreateWebhook(c *gin.Context) {
 		return
 	}
 
-	c.JSON(http.StatusCreated, gin.H{"code": 0, "data": webhook})
+	c.JSON(http.StatusCreated, gin.H{"code": 0, "message": "success", "data": webhook})
 }
 
 func (h *WebhookHandler) ListWebhooks(c *gin.Context) {
@@ -59,11 +59,14 @@ func (h *WebhookHandler) ListWebhooks(c *gin.Context) {
 	}
 
 	c.JSON(http.StatusOK, gin.H{
-		"code": 0,
-		"data": webhooks,
-		"total": total,
-		"page": page,
-		"page_size": pageSize,
+		"code":    0,
+		"message": "success",
+		"data": gin.H{
+			"list":      webhooks,
+			"total":     total,
+			"page":      page,
+			"page_size": pageSize,
+		},
 	})
 }
 
@@ -121,5 +124,5 @@ func (h *WebhookHandler) GetWebhookDeliveries(c *gin.Context) {
 		return
 	}
 
-	c.JSON(http.StatusOK, gin.H{"code": 0, "data": deliveries})
+	c.JSON(http.StatusOK, gin.H{"code": 0, "message": "success", "data": gin.H{"deliveries": deliveries}})
 }