feat: display video upload requirements

[Roopathanushree]

Description

Adds a clear upload requirements section below the video upload area so users can understand the supported file limitations before selecting a video.

The section displays:

• Maximum file size of 2 GB
• Large-file warning threshold of 500 MB
• Supported video formats
• Recommended MP4, H.264 and AAC configuration
• Browser memory and FFmpeg.wasm processing limitations
• Recommendations for smoother exports

Related Issue

Closes #1601

Type of Contribution

• New feature

Participant Info

GitHub username: Roopathanushree
Contribution level: Beginner

Testing

• The upload requirements appear before video selection
• Existing upload interaction remains functional
• Only src/components/FileUpload.tsx was modified
• No unnecessary console.log statements added

[github-actions]

✅ PR Format Check Passed — @Roopathanushree

Basic format checks passed. A maintainer will review your code changes.

This does not mean the PR is approved — it just means the format is correct.

[github-actions]

👋 Thanks for your PR, @Roopathanushree!

Welcome to Reframe — a browser-based video editor built for everyone 🎬

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Quick checklist

• PR title follows Conventional Commits (e.g. feat: add dark mode)
• Linked the issue this PR closes (e.g. Closes #123)
• Tested the changes locally (bun run dev)
• Build passes (bun run build)

Useful links

• 📖 CONTRIBUTING.md
• 🐛 Open Issues
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Happy coding! 🎉