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/(main)/settings/page.tsx

@@ -0,0 +1,7 @@
+import { redirect } from 'next/navigation'
+
+// Immediate redirect to the first settings sub-page
+// This avoids loading the heavy settings/page.tsx client component on first visit
+export default function SettingsIndexPage() {
+  redirect('/settings/general')
+}