Before JPEG encoding and OTA upload, paint the configured [[zones]]
polygons (yellow) and the [trash].roi (red) directly onto a copied
Frame.rgb so uploaded alarm snapshots visually carry the calibrated
regions. Normalized coordinates are clamped to image bounds, the source
frame stays untouched for downstream runtime processing, and
non-alert/disabled paths are unchanged. Adds stdlib-only polygon
fill/outline helpers plus focused unit tests.
Co-Authored-By: Claude <noreply@anthropic.com>
