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.
- Add file data DTO for structured file handling
- Implement file decoder service
- Update Claude and Gemini relay channels to handle various file types
- Reorganize worker service to cf_worker for clarity
- Update token counter and image service for new file types