feat: trim integration pages from 75 to 25 + migrate to MDX

- Add dedicatedPage flag to integration registry (25 true, 50 false)
- Delete hardcoded nextjs/react/vue/wordpress route pages (wrong metadata)
- Hub page routes non-dedicated integrations to /integrations/script-tag
- Add 301 redirects for 50 removed slugs → /integrations/script-tag
- Migrate guide content from TSX to MDX (content/integrations/*.mdx)
- Add gray-matter, next-mdx-remote, remark-gfm dependencies
- Add content loader (lib/integration-content.ts) matching ciphera-website pattern
- Add prebuild script for integration guide index generation
- Sitemap reduced from 83 to 35 URLs with real lastmod dates
- Remove seoDescription from registry (now in MDX frontmatter)

content/integrations/framer.mdx

@@ -0,0 +1,25 @@
+---
+title: "Framer"
+description: "Add Pulse analytics to your Framer site via custom code settings."
+category: "platform"
+brandColor: "#0055FF"
+officialUrl: "https://www.framer.com/help"
+relatedIds: ["webflow", "squarespace", "wix"]
+date: "2026-03-28"
+---
+
+Add the Pulse script to your Framer project's custom code settings.
+
+---
+
+## Add via Project Settings
+
+Go to **Project Settings -> General -> Custom Code -> Head** and paste the Pulse script.
+
+<CodeBlock filename="Project Settings -> Head">{`<script
+  defer
+  data-domain="your-site.com"
+  src="https://pulse.ciphera.net/script.js"
+></script>`}</CodeBlock>
+
+For more details, see the [Framer custom code docs](https://www.framer.com/help/articles/custom-code/).