feat: v2 — view-key payment confirmation with live monitoring

- Payment monitor: enter private view key to track incoming payments
- Scans mempool + last 100 blocks via PHP proxy with 4-node failover
- Lightweight crypto: 30KB noble-curves bundle (Ed25519 + Keccak-256)
- Subaddress support (network byte 42 detection, a*D validation)
- Confirmation progress bar (0-10 confirmations)
- Underpayment detection
- Deadline badges (7/14/30 days) replacing minutes input
- QR code: standard colors (black on white) for wallet scanner compatibility
- QR hint positioned below QR code
- View key masked input, never stored or transmitted

sw.js

@@ -1,11 +1,13 @@
-var CACHE_NAME = 'xmrpay-v1';
+var CACHE_NAME = 'xmrpay-v2';
 var ASSETS = [
   '/',
   '/index.html',
   '/app.js',
   '/i18n.js',
+  '/monitor.js',
   '/style.css',
   '/lib/qrcode.min.js'
+  // xmr-crypto.bundle.js is lazy-loaded and runtime-cached
 ];
 
 self.addEventListener('install', function (e) {
@@ -32,8 +34,8 @@ self.addEventListener('activate', function (e) {
 self.addEventListener('fetch', function (e) {
   var url = new URL(e.request.url);
 
-  // CoinGecko API — network only, don't cache
-  if (url.hostname !== location.hostname) {
+  // External APIs and RPC proxy — network only, don't cache
+  if (url.hostname !== location.hostname || url.pathname.startsWith('/api/')) {
     e.respondWith(fetch(e.request));
     return;
   }