Add remotion-video skill

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019yhnsd9RDz7jDSUUX7oEcH

.claude/skills/remotion-video/SKILL.md

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+---
+name: remotion-video
+description: Create videos from React code with Remotion. Use when the user asks to make, animate, preview, or render a video, motion graphic, intro, caption, or social clip using code.
+---
+
+# Remotion Video
+
+Remotion makes videos out of React components. Each frame is a web page. Render them in order and you get an MP4.
+
+## Core ideas
+- **Composition**: one video. Has `width`, `height`, `fps`, `durationInFrames`.
+- **Frame**: `useCurrentFrame()` returns the current frame number. All animation is a function of the frame.
+- **`interpolate`**: maps a frame range to a value range (fade, slide).
+- **`spring`**: natural bouncy motion.
+- **`Sequence`**: shows children only during a frame range.
+- **`AbsoluteFill`**: full-screen layer; stack them for backgrounds.
+- **`Audio` / `OffthreadVideo` / `Img`**: media. Put files in `public/` and load with `staticFile("name.mp3")`.
+
+## Workflow
+1. **Plan first.** Ask or decide: length (seconds), size (1920x1080, or 1080x1920 for vertical), fps (30), and the scenes. Keep scenes to a short list.
+2. **Set up** (skip if the project exists):
+   ```
+   npx create-video@latest
+   cd <project> && npm install
+   ```
+3. **Write** compositions in `src/`, register them in `src/Root.tsx`.
+4. **Preview**: `npm run dev` (opens Remotion Studio).
+5. **Render**: `npx remotion render <CompositionId> out/video.mp4`
+   Still frame: `npx remotion still <CompositionId> out/frame.png --frame=30`
+6. **Verify**: render one still first, check it looks right, then render the full video.
+
+## Starter example
+`src/Root.tsx`
+```tsx
+import { Composition } from "remotion";
+import { Hello } from "./Hello";
+
+export const RemotionRoot = () => (
+  <Composition
+    id="Hello"
+    component={Hello}
+    durationInFrames={150}
+    fps={30}
+    width={1920}
+    height={1080}
+    defaultProps={{ title: "Hello, world" }}
+  />
+);
+```
+
+`src/Hello.tsx`
+```tsx
+import { AbsoluteFill, interpolate, spring, useCurrentFrame, useVideoConfig } from "remotion";
+
+export const Hello = ({ title }: { title: string }) => {
+  const frame = useCurrentFrame();
+  const { fps } = useVideoConfig();
+  const opacity = interpolate(frame, [0, 30], [0, 1], { extrapolateRight: "clamp" });
+  const scale = spring({ frame, fps, config: { damping: 12 } });
+
+  return (
+    <AbsoluteFill style={{ backgroundColor: "#0b1020", justifyContent: "center", alignItems: "center" }}>
+      <h1 style={{ color: "white", fontSize: 120, opacity, transform: `scale(${scale})` }}>{title}</h1>
+    </AbsoluteFill>
+  );
+};
+```
+
+## Rules of thumb
+- Never animate with CSS transitions, `setTimeout`, or CSS animations. They don't render per frame. Drive everything from `useCurrentFrame()`.
+- Always pass `extrapolateRight: "clamp"` to `interpolate` unless you want values to keep growing.
+- Seconds to frames: `seconds * fps`.
+- Use `<Sequence from={..} durationInFrames={..}>` to order scenes; `<Series>` to chain them.
+- Load fonts with `@remotion/google-fonts` so they are ready before rendering.
+- Keep props in `defaultProps` so the user can edit text in the Studio.
+- Rendering needs Chromium and ffmpeg (Remotion installs/handles these); first render can be slow.
+
+## Common problems
+- **Blank/white frames**: an asset path is wrong; use `staticFile()`.
+- **Flicker**: an image or font not loaded; use `<Img>` and `@remotion/google-fonts`.
+- **Slow render**: lower resolution/fps while testing, or use `--concurrency`.
+
+## Docs
+https://www.remotion.dev/docs