Add Template, ExportOptions, BatchMode, BatchOptions, ComposeResult,
BatchResult to models.py. Keep existing ImageAsset and TransformState,
adding center() helper to TransformState.
Template uses ratio-based fields with to_transform_state() to convert
to pixel coordinates for any garment size.
BatchMode enum covers all four batch modes from PRD.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
adminandClaude Sonnet 4.6