New `sheet-music-ocr review` command that sends MusicXML output to an
LLM (Claude or OpenAI, configurable via --provider flag) for reviewing
and fixing common OCR errors like incorrect pitches, rhythms, key
signatures, and garbled lyrics. Uses httpx for direct API calls.
https://claude.ai/code/session_017GqUbuRDT58toRaxMtfRmf
