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/components/markdown-content.tsx

@@ -0,0 +1,31 @@
+'use client'
+
+import { memo } from 'react'
+import ReactMarkdown from 'react-markdown'
+import remarkGfm from 'remark-gfm'
+import remarkMath from 'remark-math'
+import rehypeKatex from 'rehype-katex'
+import 'katex/dist/katex.min.css'
+
+interface MarkdownContentProps {
+  content: string
+  className?: string
+}
+
+export const MarkdownContent = memo(function MarkdownContent({ content, className }: MarkdownContentProps) {
+  return (
+    <div dir="auto" className={`prose prose-sm prose-compact dark:prose-invert max-w-none break-words ${className}`}>
+      <ReactMarkdown
+        remarkPlugins={[remarkGfm, remarkMath]}
+        rehypePlugins={[rehypeKatex]}
+        components={{
+          a: ({ node, ...props }) => (
+            <a {...props} className="text-primary hover:underline" target="_blank" rel="noopener noreferrer" />
+          ),
+        }}
+      >
+        {content}
+      </ReactMarkdown>
+    </div>
+  )
+})