Add Remotion promo video project with 7-scene App Store flow

- Create feels-promo Remotion project for promotional videos
- Implement FeelsPromoV1 with scenes matching App Store screenshots:
  - Hero scene with mood tracking
  - Widget + Apple Watch scene
  - Journal notes with photos
  - AI-powered insights with badge
  - Privacy & security features
  - Theme customization
  - Notification styles
- Add screens folder with source assets and flow reference
- Include phone frames, widget, and watch frame assets

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

feels-promo/src/HelloWorld/Subtitle.tsx

@@ -0,0 +1,26 @@
+import React from "react";
+import { interpolate, useCurrentFrame } from "remotion";
+import { COLOR_1, FONT_FAMILY } from "./constants";
+
+const subtitle: React.CSSProperties = {
+  fontFamily: FONT_FAMILY,
+  fontSize: 40,
+  textAlign: "center",
+  position: "absolute",
+  bottom: 140,
+  width: "100%",
+};
+
+const codeStyle: React.CSSProperties = {
+  color: COLOR_1,
+};
+
+export const Subtitle: React.FC = () => {
+  const frame = useCurrentFrame();
+  const opacity = interpolate(frame, [0, 30], [0, 1]);
+  return (
+    <div style={{ ...subtitle, opacity }}>
+      Edit <code style={codeStyle}>src/Root.tsx</code> and save to reload.
+    </div>
+  );
+};