## Summary
Fix error messages in `build.sh` and add documentation in
`internal/development.md` for downloading native static libraries
(pdfium, pdf_oxide, office_oxide).
## Changes
- `build.sh`: change error hint from `uv run download_deps.py` to `uv
run ragflow_deps/download_deps.py` (correct path from project root)
- `internal/development.md`: add section 2.1 documenting how to download
native libs and install lld