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-pwa/manifest.json

@@ -0,0 +1,35 @@
+{
+  "orientation": "portrait",
+  "background_color": "#002222",
+  "theme_color": "#002222",
+  "id": "sattle",
+  "display_override": ["fullscreen", "minimal-ui"],
+  "display": "standalone",
+  "icons": [
+    {
+      "src": "icons/icon-128x128.png",
+      "sizes": "128x128",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-192x192.png",
+      "sizes": "192x192",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-256x256.png",
+      "sizes": "256x256",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-384x384.png",
+      "sizes": "384x384",
+      "type": "image/png"
+    },
+    {
+      "src": "icons/icon-512x512.png",
+      "sizes": "512x512",
+      "type": "image/png"
+    }
+  ]
+}