fix(registry): polish caption timing and add highlight style

- clip-wipe: slower reveal (0.3s), longer hold, smoother exit
- glitch-rgb: 2.5x larger RGB split, stronger scanlines, more dramatic jitter
- gradient-fill: smoother word transitions (0.15s), longer exit
- typewriter: extended group hold times so text lingers on screen
- weight-shift: per-word font-weight animation (200→900), was broken
  with only line-level shift that never triggered on single-line groups
- Add caption-highlight: red background sweep behind active word (TikTok-style)
- Re-rendered and uploaded preview videos for all 6 components

registry/registry.json

@@ -127,6 +127,10 @@
       "name": "caption-neon-glow",
       "type": "hyperframes:component"
     },
+    {
+      "name": "caption-highlight",
+      "type": "hyperframes:component"
+    },
     {
       "name": "instagram-follow",
       "type": "hyperframes:block"