feat(remotion): YC application video template + talking points

- Add YCAppVideo Remotion composition (1920x1080, 60s)
  - 3s intro card with founder name + company
  - 55s video placeholder with branded frame + lower thirds
  - 2s outro card with logo + tagline
- Update Root.tsx with new composition
- Add YC_APPLICATION_TALKING_POINTS.md with bullet points
  and recording tips per YC instructions

videos/remotion-demo/src/Root.tsx

@@ -2,6 +2,7 @@ import "./index.css";
 import { Composition } from "remotion";
 import { SquareMCPLinkedIn } from "./SquareMCPLinkedIn";
 import { SquareMCPHeroLoop } from "./SquareMCPHeroLoop";
+import { YCAppVideo } from "./YCAppVideo";
 import {
   SquareMCPTikTokCTA,
   SquareMCPTikTokDemo,
@@ -78,6 +79,14 @@ export const RemotionRoot = () => {
         width={1080}
         height={1920}
       />
+      <Composition
+        id="YCAppVideo"
+        component={YCAppVideo}
+        durationInFrames={60 * 30}
+        fps={30}
+        width={1920}
+        height={1080}
+      />
     </>
   );
 };