feat: add MOV (ProRes 4444) as transparent video output format (#224)

## Summary

- Adds `--format mov` to the render CLI for ProRes 4444 transparent video output
- ProRes 4444 with alpha is the industry standard for transparent video overlays, supported by CapCut, Final Cut, Premiere, DaVinci, and After Effects
- WebM VP9 alpha technically works but is ignored by all major video editors — only browsers decode it
- Adds MOV to the studio export dropdown alongside MP4 and WebM

## Transparency format comparison

| Format | Codec | Alpha | Video editors | Browsers | File size |
| --- | --- | --- | --- | --- | --- |
| **MOV** | ProRes 4444 | Yes | CapCut, Final Cut, Premiere, DaVinci, After Effects | No (won't play in browser) | Large (~5-40 MB) |
| **WebM** | VP9 | Yes | None (shows black) | Chrome, Firefox | Small (~200 KB) |
| **MP4** | H.264 | No | All | All | Small |

> **Note:** ProRes MOV files do not play in Chromium browsers — they are an intermediate/editing format, not a delivery format. Use [rotato.app/tools/transparent-video](https://rotato.app/tools/transparent-video) to verify transparency works correctly.

## Changes

- **CLI**: Add `mov` to `--format` validation, examples, and output path logic
- **Engine**: `getEncoderPreset()` returns ProRes 4444 (`yuva444p10le`) for `mov` format; handle `.mov` in `applyFaststart` and `muxVideoWithAudio`; add `pix_fmt` to streaming encoder ProRes path
- **Producer**: Treat `mov` like `webm` for alpha capture (PNG frames, screenshot mode, `forceScreenshot`)
- **Studio**: Add MOV option to export format dropdown and render queue hook
- **Core**: Add `mov` to studio API types, render route, and mime helpers
- **Tests**: Add encoder preset tests for mov format (42 total, all passing)

## Usage

```bash
hyperframes render --format mov --output overlay.mov
```

## Test plan

- [x] `pnpm build` passes
- [x] `pnpm --filter @hyperframes/engine test` — 42 tests pass (2 new for MOV)
- [x] `oxlint` and `oxfmt` clean on all 12 changed files
- [x] End-to-end local render produces ProRes 4444 (`yuva444p12le`) with working alpha
- [x] Docker render with `--format mov` — ProRes 4444 confirmed via ffprobe
- [x] Studio dropdown shows MOV option in built JS
- [x] Transparency verified with [rotato.app/tools/transparent-video](https://rotato.app/tools/transparent-video)

packages/studio/src/components/renders/RenderQueue.tsx

@@ -7,7 +7,7 @@ interface RenderQueueProps {
   projectId: string;
   onDelete: (jobId: string) => void;
   onClearCompleted: () => void;
-  onStartRender: (format: "mp4" | "webm") => void;
+  onStartRender: (format: "mp4" | "webm" | "mov") => void;
   isRendering: boolean;
 }
 
@@ -15,20 +15,21 @@ function FormatExportButton({
   onStartRender,
   isRendering,
 }: {
-  onStartRender: (format: "mp4" | "webm") => void;
+  onStartRender: (format: "mp4" | "webm" | "mov") => void;
   isRendering: boolean;
 }) {
-  const [format, setFormat] = useState<"mp4" | "webm">("mp4");
+  const [format, setFormat] = useState<"mp4" | "webm" | "mov">("mp4");
 
   return (
     <div className="flex items-center gap-0.5">
       <select
         value={format}
-        onChange={(e) => setFormat(e.target.value as "mp4" | "webm")}
+        onChange={(e) => setFormat(e.target.value as "mp4" | "webm" | "mov")}
         disabled={isRendering}
         className="h-5 px-1 text-[10px] rounded-l bg-neutral-800 border border-neutral-700 text-neutral-300 outline-none disabled:opacity-50"
       >
         <option value="mp4">MP4</option>
+        <option value="mov">MOV</option>
         <option value="webm">WebM</option>
       </select>
       <button

packages/studio/src/components/renders/useRenderQueue.ts

@@ -59,7 +59,7 @@ export function useRenderQueue(projectId: string | null) {
 
   // Start a render and track progress via SSE
   const startRender = useCallback(
-    async (fps = 30, quality = "standard", format: "mp4" | "webm" = "mp4") => {
+    async (fps = 30, quality = "standard", format: "mp4" | "webm" | "mov" = "mp4") => {
       if (!projectId) return;
 
       const startTime = Date.now();
@@ -96,7 +96,8 @@ export function useRenderQueue(projectId: string | null) {
       }
       const { jobId } = await res.json();
 
-      const ext = format === "webm" ? ".webm" : ".mp4";
+      const FORMAT_EXT: Record<string, string> = { mp4: ".mp4", webm: ".webm", mov: ".mov" };
+      const ext = FORMAT_EXT[format] ?? ".mp4";
       const job: RenderJob = {
         id: jobId,
         status: "rendering",