feat: fix travel placement bug, add theme-based alternate icons, fix animated background crash

- Fix repeat-city travel placement: use stop indices instead of global city name
  matching so Follow Team trips with repeat cities show travel correctly
- Add TravelPlacement helper and regression tests (7 tests)
- Add alternate app icons for each theme, auto-switch on theme change
- Fix index-out-of-range crash in AnimatedSportsBackground (19 configs, was iterating 20)
- Add marketing video configs, engine, and new video components
- Add docs and data exports

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

marketing-videos/src/components/shared/FilmGrain.tsx

@@ -0,0 +1,43 @@
+import React from "react";
+import { AbsoluteFill, useCurrentFrame } from "remotion";
+
+/**
+ * Subtle film grain overlay that makes videos feel organic/real.
+ * Uses deterministic noise per frame for reproducible renders.
+ */
+export const FilmGrain: React.FC<{ opacity?: number }> = ({
+  opacity = 0.04,
+}) => {
+  const frame = useCurrentFrame();
+  // Shift the noise pattern each frame using a CSS trick
+  const offsetX = ((frame * 73) % 200) - 100;
+  const offsetY = ((frame * 47) % 200) - 100;
+
+  return (
+    <AbsoluteFill
+      style={{
+        pointerEvents: "none",
+        mixBlendMode: "overlay",
+        opacity,
+      }}
+    >
+      <svg width="100%" height="100%">
+        <filter id={`grain-${frame % 10}`}>
+          <feTurbulence
+            type="fractalNoise"
+            baseFrequency="0.65"
+            numOctaves="3"
+            seed={frame}
+            stitchTiles="stitch"
+          />
+        </filter>
+        <rect
+          width="100%"
+          height="100%"
+          filter={`url(#grain-${frame % 10})`}
+          transform={`translate(${offsetX}, ${offsetY})`}
+        />
+      </svg>
+    </AbsoluteFill>
+  );
+};