feat: add support for compressing images

[surajkumar]

This PR adds image compression support to the KMP image selector so consumers can reduce image size before upload storage. It includes both quality-based compression and a best-effort target-size mode for requirements like keeping images under 5 MB.

What Changed

• Added a shared compression API for ByteArray and ImageData
  Introduced ImageCompressionOptions and ImageCompressionFormat
• Added compress(...) for quality-based compression
• Added compressToMaxBytes(...) for best-effort size targeting
• Implemented platform-specific compression for Android, iOS, and Desktop/JVM
• Documented the new API in the README

Examples:

val compressed = imageData.compress(
    ImageCompressionOptions(
        quality = 88
    )
)

val underFiveMb = imageData.compressToMaxBytes(
    maxBytes = 5L * 1024L * 1024L
)

Additionally, fixes a bug with iOS hanging.