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).

postcss.config.js

@@ -0,0 +1,30 @@
+// https://github.com/michael-ciniawsky/postcss-load-config
+
+import autoprefixer from 'autoprefixer';
+// import rtlcss from 'postcss-rtlcss'
+// import { Mode } from 'postcss-rtlcss/options'
+
+export default {
+  plugins: [
+    // https://github.com/postcss/autoprefixer
+    autoprefixer({
+      overrideBrowserslist: [
+        'last 4 Chrome versions',
+        'last 4 Firefox versions',
+        'last 4 Edge versions',
+        'last 4 Safari versions',
+        'last 4 Android versions',
+        'last 4 ChromeAndroid versions',
+        'last 4 FirefoxAndroid versions',
+        'last 4 iOS versions',
+      ],
+    }),
+
+    // https://github.com/elchininet/postcss-rtlcss
+    // If you want to support RTL css, then
+    // 1. yarn/pnpm/bun/npm install postcss-rtlcss
+    // 2. optionally set quasar.config.js > framework > lang to an RTL language
+    // 3. uncomment the following line (and its import statement above):
+    // rtlcss({ mode: Mode.Override })
+  ],
+};