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).

.vscode/extensions.json

@@ -0,0 +1,15 @@
+{
+  "recommendations": [
+    "dbaeumer.vscode-eslint",
+    "esbenp.prettier-vscode",
+    "editorconfig.editorconfig",
+    "vue.volar",
+    "wayou.vscode-todo-highlight"
+  ],
+  "unwantedRecommendations": [
+    "octref.vetur",
+    "hookyqr.beautify",
+    "dbaeumer.jshint",
+    "ms-vscode.vscode-typescript-tslint-plugin"
+  ]
+}