feat: add image management functionality

- Implemented image folder repository with CRUD operations.
- Added image reference repository for managing image references to articles.
- Created image repository for handling image assets, including listing, inserting, updating, and deleting images.
- Introduced image usage repository to track storage usage and quotas for tenants.
- Added SQL queries for image assets, folders, references, and usage.
- Developed image handler for HTTP endpoints to manage images and folders.
- Created database migration scripts for image-related tables and structures.

server/internal/shared/objectstorage/aliyun.go

@@ -158,6 +158,36 @@ func (c *aliyunClient) GetBytes(ctx context.Context, objectKey string) ([]byte,
 	return data, nil
 }
 
+func (c *aliyunClient) Exists(ctx context.Context, objectKey string) (bool, error) {
+	if err := c.Validate(); err != nil {
+		return false, err
+	}
+	if strings.TrimSpace(objectKey) == "" {
+		return false, nil
+	}
+
+	bucket, err := c.client.Bucket(c.bucket)
+	if err != nil {
+		c.logError(ctx, "aliyun get bucket failed",
+			zap.String("bucket", c.bucket),
+			zap.String("object_key", objectKey),
+			zap.Error(err),
+		)
+		return false, fmt.Errorf("get aliyun bucket: %w", err)
+	}
+
+	exists, err := bucket.IsObjectExist(objectKey)
+	if err != nil {
+		c.logError(ctx, "aliyun stat object failed",
+			zap.String("bucket", c.bucket),
+			zap.String("object_key", objectKey),
+			zap.Error(err),
+		)
+		return false, fmt.Errorf("stat aliyun object: %w", err)
+	}
+	return exists, nil
+}
+
 func (c *aliyunClient) Delete(ctx context.Context, objectKey string) error {
 	if err := c.Validate(); err != nil {
 		return err