fix(exif): use original HEIC buffer for EXIF extraction

[xxxbrian]

Summary

• Use original HEIC buffer instead of heicConvert processed data for EXIF extraction
• Fix missing EXIF data issue with HEIC files

Problem

When processing HEIC files, we use heicConvert to convert them to JPEG format. However, some EXIF data gets lost during this conversion process.

Solution

// Before
await writeFile(tempImagePath, imageBuffer)

// After  
await writeFile(tempImagePath, originalBuffer || imageBuffer)

For HEIC files, use the original buffer for EXIF extraction to preserve all metadata. For other formats, continue using the processed buffer.