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).

env.d.ts

@@ -0,0 +1,15 @@
+/**
+ * Add types (that are not auto-magically added by Quasar CLI already)
+ * for your custom variables to avoid TypeScript errors, like dynamic
+ * process.env variables or definitions in dotenv files configured ONLY
+ * for the /quasar.config file itself.
+ *
+ * https://quasar.dev/quasar-cli-vite/handling-import-meta-env#type-inference
+ *
+ * @example
+ * interface ImportMetaEnv {
+ *   readonly MY_VAR: string;
+ *   readonly MY_OTHER_VAR: string;
+ * }
+ */
+interface ImportMetaEnv {}