[NePreby]

Summary

Closes #11.

Adds a mobile verification QR code to ReceiptModal encoding the transaction's block explorer URL:

1. Lightweight Zero-Dependency QR Generator (frontend/src/lib/qr.ts):
   • Implements QR Code Model 2 (Byte mode, Reed-Solomon error correction, version auto-scaling 1-10).
   • Generates compact inline SVG path strings (qrToSvgPath) for pixel-crisp rendering without blurry canvas scaling or external dependencies.
2. ReceiptModal Integration (frontend/src/components/ReceiptModal.tsx):
   • Positioned cleanly directly beneath the deterministic verification badges.
   • Encodes ${config.explorer}/tx/${r.tx_hash} (Stellar Expert testnet transaction explorer URL).
   • Designed in the Architectural Drafting style (framed white background container, hairline borders, and live link with open icon).
3. Unit Tests & Verification (frontend/src/lib/__tests__/qr.test.ts):
   • Unit tests covering QR matrix sizing, finder pattern structure, and SVG path generation.
   • Verified clean with npx tsc -b and npx vitest run (50/50 tests passing across 7 test suites).

Payout Wallet:

• TRX Tron (TRC20): TMqmJjRgVS21NL2eFtfyHciTxvE4BqGmEv