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).

vitest.config.ts

@@ -0,0 +1,13 @@
+import { defineConfig } from 'vitest/config';
+
+export default defineConfig({
+  test: {
+    // the tested modules are pure crypto/codec helpers - node's own
+    // WebCrypto (crypto.subtle) covers everything they need, no jsdom
+    environment: 'node',
+    include: ['src/**/*.test.ts'],
+    // protocol tests live in lnurlcash-kit (its conformance suite); app tests
+    // arrive with M2 flows. Don't fail CI until then.
+    passWithNoTests: true,
+  },
+});