Add Native HEIC Support and Fix EXIF Orientation

[Kundan-Krishna366]

Description

This PR adds native support for HEIC/HEIF image formats (commonly used by iOS devices) and addresses an issue where mobile uploads appear incorrectly rotated in the processed output.

Key Changes:

• HEIF/HEIC Support: Integrated pillow-heif to enable decoding of Apple-native image formats in the FastAPI backend.
• Orientation Correction: Implemented ImageOps.exif_transpose to ensure images respect their original EXIF orientation metadata before processing.
• Pipeline Standardization: Forced RGBA conversion to ensure consistency across all inference models.
• Documentation: Updated remove_background_endpoint docstrings to follow the project's Google-style standard.

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Type of Change

• feat - New feature (MINOR version bump)
• fix - Bug fix (PATCH version bump)
• docs - Documentation only
• style - Code style/formatting

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Checklist

• My commit messages follow the Conventional Commits format.
• I have updated the documentation (Docstrings in main.py).
• All tests are passing locally on Arch Linux.
• My code follows the project's style guidelines (black + ruff).

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Related Issues

Closes #7

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Testing

Verified locally using uv on Arch Linux (Python 3.12):

1. Format Support: Uploaded .heic files via Swagger UI and confirmed successful processing.
2. Orientation: Confirmed that Portrait-mode photos are correctly oriented in the output.
3. Stability: Verified that standard .png and .jpg processing remains unaffected.

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Screenshots

Successful HEIC Processing (Swagger UI):

📝 Note: When this PR is merged to main, an automated release will be triggered based on your commit messages.