feat(compress_images): add jpeg format support

[yxlao]

Summary

Adds JPEG format support to the compress_images tool, enabling users to output images with .jpeg extension in addition to the existing .jpg support.

Changes Made

• Added "jpeg" to the --format argument choices and updated help text
• Updated get_operation_string() to return operation strings for both "jpg" and "jpeg" formats (e.g., "PNG→JPEG Q90")
• Modified entry_point() to treat jpeg same as jpg for same-format compression logic
• Updated is_same_format check to include args.format in ["jpg", "jpeg"]
• Added conditional suffix handling to use .jpeg extension when output format is jpeg
• Updated error message to reference "JPG/JPEG" instead of just "JPG"
• Updated compression ratio skip logic to apply to both jpg and jpeg
• Added documentation example: ct compress-images image.png --format jpeg --quality 90