refactor(skills): move image catalogs to references

Keep the decision steps in SKILL.md and move catalogs, examples, and
checklists verbatim to references/ to reduce the context cost of loading the
skill.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

shared/skills/image/references/og-social-preview-images.md

@@ -0,0 +1,23 @@
+# OG & Social Preview Images
+
+The image that appears when your URL is shared on social media, Slack, Discord, etc.
+
+## Required Meta Tags
+
+```html
+<meta property="og:image" content="https://yoursite.com/og/page-name.jpg" />
+<meta property="og:image:width" content="1200" />
+<meta property="og:image:height" content="630" />
+<meta name="twitter:card" content="summary_large_image" />
+<meta name="twitter:image" content="https://yoursite.com/og/page-name.jpg" />
+```
+
+## Dynamic OG Images
+
+Generate OG images programmatically for pages with dynamic content (blog posts, user profiles):
+
+- **Vercel OG** (`@vercel/og`) — generates images at the edge using JSX
+- **Satori** — converts HTML/CSS to SVG (powers Vercel OG)
+- **Cloudinary** — URL-based text overlay on template images
+
+**Best for programmatic SEO:** Generate unique OG images per page using templates + dynamic data.