When running in i2i (image-to-image) mode, the script passes a
base64-encoded image as a jq argument on the command line. On Windows,
cmd.exe limits arguments to ~32 KB, causing 'Argument list too long' errors
when the reference image is large.
Fix: write intermediate JSON fragments to temp files and pass them to jq
via --from-file instead of on the command line. This works reliably on
Windows and is equally valid on Linux/macOS.
Fixes the i2i (--mode i2i --ref-image) workflow on Windows.
b4e6c16f4b