Init Chunked Upload

**Initialize Chunked Upload** **Validation Rules:** - `filename` (required): Name of the file - Required - String - Max length: 255 characters - `file_size` (required): Total file size in bytes - Required - Integer - Min: 1 - `mime_type` (required): MIME type of the file - Required - String - Max length: 255 characters - `media_type` (required): Type of media - Required - Must be one of: photo, video, audio, document, drawing, signature, before_photo, after_photo, progress_photo, damage_photo, part_photo, measurement, inspection, safety, compliance, other - `chunk_size` (optional): Size of each chunk in bytes - Optional - Integer - Min: 1 - `total_chunks` (required): Total number of chunks - Required - Integer - Min: 1 **Response:** Returns upload_id to use in subsequent chunk upload requests