uhttpd-mod-ubus silently rejects JSON-RPC requests >64KB with "Parse error",
causing uploads of .py files >48KB to fail with "No related RPC reply".
- Add chunked upload (upload_chunk + upload_finalize) that splits base64
content into 40KB pieces sent sequentially, then reassembles server-side
- Frontend auto-selects chunked upload when content exceeds 40KB
- Stop polling during upload to prevent RPC batch conflicts
- RPCD handlers use cat-to-tempfile instead of shell variables for stdin
to avoid BusyBox argument size limits
- Container startup script handles top-level .py files (not just subdirs)
- streamlitctl cmd_instance_start also handles top-level .py files
- Add upload_chunk and upload_finalize to ACL
Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>