Add Bulk giftcards extension

[bitkarrot]

Summary

• Adds the Gift Cards extension (bitkarrot/giftcards) to the registry.
• Create and redeem sats-denominated gift cards with unique secure links.
• FUTURE PLAN: to make extension handle LNURLCash (not this version, but next one)

Features

• Single & bulk creation — Create one card or hundreds via CSV upload
• Custom card design — Drag-and-drop QR/text placement, font controls, color pickers, portrait/landscape templates, or upload your own template image
• Secure redemption — Each card gets a unique, unguessable token and shareable link; recipients redeem by scanning a QR code with any Lightning wallet
• Email delivery — Send branded gift card images directly to recipients via email
• Printable PNG — Download high-resolution (3x) card images for manual distribution
• Expiration & auto-refund — Set expiration dates; unclaimed sats are automatically returned to the issuer wallet
• Issuer dashboard — Filter, search, and manage all cards with bulk actions (email, CSV export, delete)

Extension details

Field	Value
id	giftcards
repo	https://github.com/bitkarrot/giftcards
version	0.2.2
min_lnbits_version	1.5.4
license	MIT

A LICENSE file was added to the giftcards repo and the version bumped to 0.2.1 so the release archive satisfies the registry's mandatory-file checks. v0.2.2 additionally fixes an install failure caused by importing run_interval from lnbits.tasks (not available on LNbits dev); the extension now uses the standard asyncio periodic loop pattern.

Verification

• extensions.json is valid JSON
• check.py giftcards passes (archive hash matches, icon resolves, min_lnbits_version matches config.json, all mandatory files present in the archive)
• jmeter CI passes (extension installs, enables, and serves GET /giftcards/ 200)