sattle: Quasar PWA scaffold with lnurlcash-kit protocol core

M1: Quasar 2 / Vue 3 / TS / Pinia / i18n / PWA app shell in the lnurl-wallet
palette (#002222/#004444/#55ffcc, Noto Sans). Protocol layer is the external
lnurlcash-kit library (git dependency on the fork until upstream merges the
prepare fix / publishes to npm); keys.ts + receive.ts vendored from
lnurl-wallet with the derivation domain renamed to 'sattle'. Nix dev shell,
ci workflow (typecheck, vitest, pwa build).

src/css/app.scss

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+// app global css - sattle's visual identity is inherited from lnurl-wallet
+// (see src/lnurlcash/ provenance): dark teal surfaces, mint-green accents
+
+@import '@fontsource/noto-sans/400.css';
+@import '@fontsource/noto-sans/700.css';
+
+body {
+  font-family: 'Noto Sans', sans-serif;
+  background: linear-gradient(160deg, #001616 0%, #002222 55%, #001a1a 100%);
+  background-attachment: fixed;
+  color: #55ffcc;
+}
+
+// glassy dark-teal card surface, lnurl-wallet style
+.sattle-card {
+  background: rgba(0, 68, 68, 0.6);
+  border-radius: 8px;
+  backdrop-filter: blur(4px);
+}

src/css/quasar.variables.scss

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+// Quasar Sass (& SCSS) Variables
+// --------------------------------------------------
+// sattle's visual identity is inherited from lnurl-wallet (dark teal +
+// mint green). Exact values from lnurl-wallet's src/styles/style.scss:
+//   bg #002222, accent base #004444, primary #55ffcc,
+//   warning #ff8800, negative #ff4444, spent #ff6666,
+//   signed badge #66cc66, device badge #6699cc
+
+$primary: #55ffcc;
+$secondary: #004444;
+$accent: #004444;
+
+$dark: #002222;
+$dark-page: #001616;
+
+$positive: #66cc66;
+$negative: #ff4444;
+$info: #6699cc;
+$warning: #ff8800;
+
+// extra lnurl-wallet palette tokens, for use in app.scss / components
+$spent: #ff6666;
+$bg-glow: #001a1a;