fix(registry): align timeline IDs and regenerate catalog index

- Fix timeline_id_mismatch on all 15 caption components: __timelines key
  now matches data-composition-id (e.g. "caption-clip-wipe" not "clip-wipe")
- Regenerate docs/public/catalog-index.json with 15 new caption entries
- Add "Captions" group mapping to generate-catalog-pages.ts (priority 0)
- Regenerate docs.json nav and mdx pages via the catalog script
- Upload docs preview videos to docs/images CDN path

registry/components/caption-editorial-emphasis/caption-editorial-emphasis.html

@@ -424,7 +424,7 @@
       });
 
       tl.to({}, { duration: DURATION }, 0);
-      window.__timelines["editorial-emphasis"] = tl;
+      window.__timelines["caption-editorial-emphasis"] = tl;
     </script>
   </body>
 </html>

registry/components/caption-editorial-emphasis/demo.html

@@ -424,7 +424,7 @@
       });
 
       tl.to({}, { duration: DURATION }, 0);
-      window.__timelines["editorial-emphasis"] = tl;
+      window.__timelines["caption-editorial-emphasis"] = tl;
     </script>
   </body>
 </html>