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/ai/ai-settings-header.tsx

@@ -0,0 +1,16 @@
+'use client'
+
+import { useLanguage } from '@/lib/i18n'
+
+export function AISettingsHeader() {
+  const { t } = useLanguage()
+
+  return (
+    <div className="mb-6">
+      <h1 className="text-3xl font-bold">{t('aiSettings.title')}</h1>
+      <p className="text-gray-600 dark:text-gray-400">
+        {t('aiSettings.description')}
+      </p>
+    </div>
+  )
+}