parseHEIFDimensions now correctly handles boxSize==1 (64-bit extended
size) and boxSize==0 (box-to-EOF), preventing the parser from breaking
out of the loop when encountering these valid ISOBMFF box headers
before reaching the meta box.
Add detection, MIME type mapping, and dimension parsing for HEIC/HEIF
images via ISOBMFF ftyp brand inspection and ispe box parsing. Update
Gemini relay to accept these formats and refactor getImageConfig to
properly retry decoders using buffered data.