Add animated rainbow gradient to Outer Limits easter egg text

Opening narration cycles through a 9-stop gradient (red → amber →
yellow → green → teal → blue → violet → pink → red) at 6s per
loop. Closing narration stays teal for visual hierarchy.

docs/src/styles/oscilloscope.css

@@ -381,10 +381,25 @@
   font-family: 'Georgia', 'Times New Roman', serif;
   font-size: 0.65rem;
   line-height: 1.6;
-  color: var(--scope-teal);
   text-align: center;
-  text-shadow: 0 0 8px var(--scope-teal-glow);
   margin: 0;
+  /* Animated rainbow gradient text */
+  background: linear-gradient(
+    90deg,
+    #ff6b6b, #ffb347, #ffd93d, #a3ff6b,
+    #2dd4bf, #6bb5ff, #c084fc, #ff6b9d, #ff6b6b
+  );
+  background-size: 300% 100%;
+  -webkit-background-clip: text;
+  background-clip: text;
+  -webkit-text-fill-color: transparent;
+  animation: scope-rainbow 6s linear infinite;
+  filter: drop-shadow(0 0 6px rgba(255, 255, 255, 0.15));
+}
+
+@keyframes scope-rainbow {
+  0% { background-position: 0% center; }
+  100% { background-position: 300% center; }
 }
 
 /* Closing narration + plug — fades in after typewriter finishes */