Add Thomas Lübker testimonial to customers page (#43830)

## Summary
- Adds a new testimonial from Thomas Lübker to the Fleet
customers/testimonials page
- Quote: "I think it is key that people understand the leverage they
have with AI if everything is 'code'. In the AI age, clickops will not
prevail!"
- Anonymous-style testimonial (no company logo) with LinkedIn profile
link

### Changes
- `handbook/company/testimonials.yml` — added new testimonial entry
- `website/assets/images/testimonial-author-thomas-luebker-48x48@2x.png`
— added profile image placeholder

---

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Co-authored-by: kiloconnect[bot] <240665456+kiloconnect[bot]@users.noreply.github.com>

handbook/company/testimonials.yml

@@ -8,7 +8,13 @@
 #   youtubeVideoUrl:
 #.  productCategories: [Observability, Software management, Device management]
 #
-# TODO figure out what to do with this other quote that both Austin and Dre :+1:'d: "Fleet lets us be more actionable with fewer people. It helps us to filter out the noise better than we could with the other big name products we replaced."
+# TODO figure out what to do with this other quote that both Austin and Dre :+1:'d: "Fleet lets us be more actionable with fewer people. It helps us to filter out the noise better than we could with the other big name products we replaced."
+- quote: I think it is key that people understand the leverage they have with AI if everything is 'code'. In the AI age, clickops will not prevail!
+  quoteAuthorName: Thomas Lübker
+  quoteAuthorProfileImageFilename: testimonial-author-thomas-luebker-48x48@2x.png
+  quoteLinkUrl: https://www.linkedin.com/in/tluebker/?skipRedirect=true
+  quoteAuthorJobTitle: Helping Apple devices take off in the enterprise
+  productCategories: [Device management]
 - quote: Fleet is incredibly easy to deploy and perfect for lean IT teams. It's everything we need in a device management platform, simple, efficient, and powerful.
   quoteAuthorName: Chayce O'Neal
   quoteAuthorProfileImageFilename: testimonial-author-chayce-oneal-100x100@2x.png