feat(studio): render queue, layout restructure, home page, hover preview (#95)

## Summary
- Add render queue panel with progress tracking, download, and delete actions
- Restructure App layout: home page with project picker, session-based routing
- Add ExpandOnHover component for preview-on-hover interactions (uses motion/react)
- CompositionsTab now supports hover preview with expanded iframe view
- Vite config: guard setInterval cleanup to dev-only (fixes CI build timeout)
- Add favicon and update studio package deps

## Test plan
- [x] Render queue shows progress, completes, and allows download
- [x] Home page lists projects and navigates to session view
- [x] ExpandOnHover shows expanded preview on mouse hover with spring animation
- [x] `vite build` exits cleanly (no hanging process from setInterval)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

packages/studio/src/player/components/VideoThumbnail.tsx

@@ -1,4 +1,5 @@
 import { memo, useRef, useState, useCallback, useEffect } from "react";
+import { useMountEffect } from "../../hooks/useMountEffect";
 
 interface VideoThumbnailProps {
   videoSrc: string;
@@ -55,15 +56,15 @@ export const VideoThumbnail = memo(function VideoThumbnail({
     roRef.current.observe(target);
   }, []);
 
-  useEffect(
-    () => () => {
-      ioRef.current?.disconnect();
-      roRef.current?.disconnect();
-    },
-    [],
-  );
+  useMountEffect(() => () => {
+    ioRef.current?.disconnect();
+    roRef.current?.disconnect();
+  });
 
-  // Extract frames progressively — each frame appears as soon as it's ready
+  // Extract frames progressively — each frame appears as soon as it's ready.
+  // Note: useEffect with deps is acceptable — syncs with external video element API,
+  // requires cleanup (cancel extraction, revoke URLs) when inputs change.
+  // eslint-disable-next-line no-restricted-syntax
   useEffect(() => {
     if (!visible || extractingRef.current) return;
     extractingRef.current = true;