feat(dataset): add CreateML format support to DetectionDataset (#2284)
- Added CreateML import/export support for detection datasets, including pixel-space center/width/height box conversion, class-name inference, global class-id consistency, and image path safety validation.
- Added optional progress bars for CreateML loading, exporting, and image saving.
- Improved CreateML validation with clear errors for malformed JSON, missing fields, duplicate images, null annotations, and unsafe image paths.
- Updated dataset documentation and references to include CreateML workflows and `from_createml` / `as_createml` usage.
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Co-authored-by: jirka <6035284+Borda@users.noreply.github.com>
Co-authored-by: claude[bot] <209825114+claude[bot]@users.noreply.github.com>
Co-authored-by: Codex <codex@openai.com>
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