Support resumable mobile catalogue pages

[sridharkalaibala]

Mobile catalogues no longer have to fit inside one MongoDB grant or restart their full transfer after an interruption. Authenticated immutable pages are scoped to the issuing shop, branch, user and device. Old price grants remain usable for delayed sales, while unchanged pages can be reused and deleted items disappear after activation.

Product image references and revisions are included for the mobile persistent cache. Existing clients retain the original bootstrap response. Catalogue pages stay local to the issuing server. API documentation is regenerated.

Validation: 440 API suites / 11,569 tests passed (13 existing skips); 3,631 desktop tests passed (5 existing skips); all 21 real-database/mobile-browser integration cases passed, including 10,017 additional items, device isolation, price changes, deletion, page reuse, offline sale replay and image persistence after restart. Targeted ESLint has zero errors; attribution and badge checks pass. The Windows beta installer was assembled and its API/desktop payload compared with source.

[github-actions]

Merged to develop. Anyone can test this - you do not need write access.

Try it at https://develop.posnic.io, or run it yourself:

git fetch origin develop && git checkout develop
npm install && npm --prefix api install
npm run dev   # then http://localhost:3000

When you have tested it, say what you did and what happened, and set
QA passed or QA failed. If you cannot set labels, just comment -
a maintainer will.

Reporting that something is broken is as useful as fixing it. It is
better found here than by a shopkeeper.