chore: clean up repo for public release

- Remove BMAD framework, IDE configs, dev screenshots, test files,
  internal docs, and backup files
- Rename keep-notes/ to memento-note/
- Update all references from keep-notes to memento-note
- Add Apache 2.0 license with Commons Clause (non-commercial restriction)
- Add clean .gitignore and .env.docker.example

memento-note/app/(auth)/layout.tsx

@@ -0,0 +1,19 @@
+'use client';
+
+import { LanguageProvider } from '@/lib/i18n/LanguageProvider';
+
+export default function AuthLayout({
+  children,
+}: Readonly<{
+  children: React.ReactNode;
+}>) {
+  return (
+    <LanguageProvider>
+      <div className="flex min-h-screen items-center justify-center bg-gray-50 dark:bg-zinc-950">
+        <div className="w-full max-w-md p-4">
+          {children}
+        </div>
+      </div>
+    </LanguageProvider>
+  );
+}