Remove unnecessary receipt initialization wait

[sridharkalaibala]

Ready Windows printers could wait up to 30 seconds for a separate initialization or idle job before receiving the receipt. Send the receipt, which already starts with ESC @, immediately after readiness checks. Preserve offline recovery, printer identity checks, per-printer serialization and duplicate protection.

Fast receipt now converts GBP/EUR symbols to printable currency codes instead of silently switching to image rendering.

Validation: 139 targeted tests passed; four delay regressions fail on the original code and pass with the fix. Six real Electron renders (58/80 mm, 12 strips each) completed in 271–526 ms. These timings cover rendering only, not physical printing. Client installation and device verification are still pending.

[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.