feat: rename keep-notes to memento-note, migrate to PostgreSQL, fix MCP bugs

- Rename directory keep-notes -> memento-note with all code references
- Prisma: SQLite -> PostgreSQL (both app and MCP server schemas)
- Sync MCP schema with main app (add missing fields, relations, indexes)
- Delete 17 SQLite migrations (clean slate for PostgreSQL)
- Remove SQLite dependencies (@libsql/client, better-sqlite3, etc.)
- Fix MCP server: hardcoded Windows DB paths -> DATABASE_URL env var
- Fix MCP server: .dockerignore excluded index-sse.js (SSE mode broken)
- MCP Dockerfile: node:20 -> node:22
- Docker Compose: add postgres service, remove SQLite volume
- Generate favicon.ico, icon-192.png, icon-512.png, apple-icon.png
- Update layout.tsx icons and manifest.json for PNG icons
- Update all .env files for PostgreSQL
- Rewrite README.md with updated sections
- Remove mcp-server/node_modules and prisma/client-generated from git tracking

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

memento-note/components/markdown-content.tsx

@@ -0,0 +1,30 @@
+'use client'
+
+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 function MarkdownContent({ content, className = '' }: MarkdownContentProps) {
+  return (
+    <div 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>
+  )
+}