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/components/caption-glitch-rgb/demo.html

@@ -56,8 +56,8 @@
           to bottom,
           transparent 0px,
           transparent 3px,
-          rgba(0, 0, 0, 0.08) 3px,
-          rgba(0, 0, 0, 0.08) 4px
+          rgba(0, 0, 0, 0.18) 3px,
+          rgba(0, 0, 0, 0.18) 4px
         );
       }
       #gl-container {
@@ -240,10 +240,10 @@
             var wordEl = document.getElementById("gl-w-" + wi);
             var isKW = KEYWORDS.has(wi);
             var rng = mulberry32(wi * 777 + 13);
-            var j1 = (rng() - 0.5) * 10;
-            var j2 = (rng() - 0.5) * 8;
-            var j3 = (rng() - 0.5) * 6;
-            var shadowMag = 3 + rng() * 4;
+            var j1 = (rng() - 0.5) * 24;
+            var j2 = (rng() - 0.5) * 18;
+            var j3 = (rng() - 0.5) * 14;
+            var shadowMag = 6 + rng() * 8;
             var sm = shadowMag.toFixed(1);
 
             tl.to(