v1.30.0 — don't force OCR; route file requests by intent

Auto-OCR used to fire whenever you named image/PDF files, OCR-ing them regardless of intent (slow, and big PDFs built multi-MB prompts). Now chati routes by what you asked: compare/dedupe/size/date gives a metadata table (size, modified, SHA-256) plus a real text diff when files have extractable text (no OCR; identical SHA-256 = duplicate); read/analyze/extract or a bare file drop still OCRs; a file named with no read/compare intent shows its metadata and offers /ocr instead of silently OCR-ing. New helpers: msg_wants_compare, detect_files_in_msg, msg_is_just_paths, files_metadata_summary, file_text_cheap. Suite: 126 passed. (#66)