PicToPC 0.7.9 — Gumtree support

Adds a fixed bottom-right Insert PicToPC photos button on https://www.gumtree.com/postad/next (and the non-www equivalent). Same controls are available in the extension popup.

Choose a group with Send to marketplace in PicToPC. Keep that library open. On Gumtree Post an Ad, click Insert PicToPC photos. Title and description are selected by default; Add SKU appends a public SKU: code line without warehouse location. Untick this option to keep SKU private. Blank source descriptions retain existing description. SKU-only insertion preserves existing description and avoids repeating the identical final SKU line.

Up to 20 photos in total, including existing draft photos. Larger groups can explicitly choose the first 20; the remainder stay in PicToPC. Unsupported video is not transferred. Price, category, condition, contact information, promotions and posting are left for the user.

Security: exact HTTPS domain and listing-route allowlist; top-frame document-bound source transfer; no new host permissions; narrowly scoped postad content script. Photos upload only after preflight checks for capacity, field lengths and unchanged draft. Original photo bytes stay unchanged unless compatible copies were selected and required.

Validated DOM selectors on the signed-in Gumtree editor. Offline regression tests cover 20-photo boundaries, existing counts, title and description limits, separate SKU privacy, changed drafts, original bytes, no replay, overlay stability, popup and worker authorization. Existing Facebook and eBay checks pass. Actual installed-extension upload acceptance still needs a live user check. This ZIP has not been submitted to the Chrome Web Store.

Extract ZIP, reload the unpacked extension in Chrome, refresh PicToPC and Gumtree, and select the group again. Refreshing PicToPC is necessary for the new separate SKU field.
