🎬 Add PortalIntroScene component for Logo Reveal (Scene 1)

Implement the first scene of the Portal presentation video (6 seconds):
- AnimatedLogo scales from 0 to 100% with spring animation
- Wallpaper background with zoom effect (1.2 → 1.0 scale)
- Bitcoin particle effects in the background
- Pulsing glow effect around the logo
- Audio integration: logo-whoosh at start, logo-reveal when logo appears
- Title "EINUNDZWANZIG" and subtitle "Das Portal" with staggered entrance
- Vignette overlay for cinematic depth

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

videos/src/PortalPresentation.tsx

@@ -1,5 +1,6 @@
 import { AbsoluteFill, Sequence, useVideoConfig, Img, staticFile } from "remotion";
 import { inconsolataFont } from "./fonts/inconsolata";
+import { PortalIntroScene } from "./scenes/portal/PortalIntroScene";
 
 /**
  * PortalPresentation - Main composition for the Einundzwanzig Portal presentation video
@@ -124,7 +125,7 @@ export const PortalPresentation: React.FC = () => {
         durationInFrames={sceneFrames.logoReveal.duration}
         premountFor={fps}
       >
-        <PlaceholderScene name="Logo Reveal" sceneNumber={1} />
+        <PortalIntroScene />
       </Sequence>
 
       {/* Scene 2: Portal Title (4s) */}