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/lib/useMountEffect.ts

@@ -1,10 +0,0 @@
-import { useEffect } from "react";
-
-/**
- * Run an effect exactly once on mount (and optional cleanup on unmount).
- * This is the ONLY sanctioned way to call useEffect in this package.
- */
-export function useMountEffect(effect: () => void | (() => void)) {
-  // eslint-disable-next-line react-hooks/exhaustive-deps
-  useEffect(effect, []);
-}