feat: enhance markdown note blocks with style options and double-click config access

- Added support for configuring markdown note block styles, including color and opacity.
- Enabled double-click on markdown notes to open their configuration dialog.
- Adjusted layout styles in markdown previews for better interaction control.
- Updated relevant payloads, types, and UI logic to support added styling features.
- Integrated multiple example notes in learning recipes for better visualization.

studio/frontend/src/components/markdown/markdown-preview.tsx

@@ -23,7 +23,7 @@ function MarkdownPreviewImpl({
     <div
       className={cn(
         plain
-          ? "nodrag h-full w-full overflow-auto p-2 text-xs leading-relaxed"
+          ? "h-full w-full overflow-auto p-2 text-xs leading-relaxed pointer-events-none select-none"
           : "nodrag max-h-56 overflow-auto rounded-md border border-border/60 bg-muted/20 p-2 text-xs leading-relaxed",
         className,
       )}