feat: wallet operations engine and encrypted storage with tests

src/lnurlcash/test-utils.ts

@@ -0,0 +1,28 @@
+// Shared test scaffolding: an in-memory localStorage (Node has none outside
+// a browser) plus the mock-mint helpers every suite uses.
+
+import {vi} from 'vitest'
+
+export class LocalStorageStub {
+  private map = new Map<string, string>()
+  getItem = (key: string): string | null => this.map.get(key) ?? null
+  setItem = (key: string, value: string): void => {
+    this.map.set(key, String(value))
+  }
+  removeItem = (key: string): void => {
+    this.map.delete(key)
+  }
+  clear = (): void => {
+    this.map.clear()
+  }
+  get length(): number {
+    return this.map.size
+  }
+  key = (index: number): string | null => [...this.map.keys()][index] ?? null
+}
+
+export const stubLocalStorage = (): LocalStorageStub => {
+  const stub = new LocalStorageStub()
+  vi.stubGlobal('localStorage', stub)
+  return stub
+}