Old juc500_app processes kept serving pre-fix code; start.sh now
kills them and GUI defaults to port 8766.
Co-authored-by: Cursor <cursoragent@cursor.com>
Restores the helper accidentally removed when adding access-denied
handling, retries I/O after seeding pyusb config index on Windows, and
handles USB overflow reads without crashing the HELLO loop.
Co-authored-by: Cursor <cursoragent@cursor.com>