fix: update live preview for framing and aspect ratio changes

[srinidhi-2006-bit]

Description

• Fixed live preview not updating when changing output aspect ratio
• Added dynamic preview container aspect ratio support
• Synced Fit/Fill framing modes with live preview
• Ensured preview behavior matches exported video output

Related Issue

Closes #812

Type of Contribution

• Bug fix
• New feature
• Documentation update
• GSSoC contribution

Participant Info

• GitHub username: srinidhi-2006-bit
• Contribution level: Beginner

Screen Recording

Recording / Loom link: https://www.loom.com/share/e07dcc2e2cf7438cb1ceca387365d376

Checklist

• I have read the contribution guidelines
• My changes follow the project structure
• I have tested my changes in Chrome, Firefox, and Safari
• bun run lint passes (no ESLint errors)
• bunx tsc --noEmit passes (no TypeScript errors)
• New interactive elements have aria-label / accessible names
• No console.log statements left in
• This PR is related to a valid issue
• Screen recording attached above

[vercel]

@srinidhi-2006-bit is attempting to deploy a commit to the magic-peach1's projects Team on Vercel.

A member of the Team first needs to authorize it.

[github-actions]

👋 Thanks for your PR, @srinidhi-2006-bit!

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

🟠 GSSoC'26 PR detected — thanks for contributing under GirlScript Summer of Code 2026!

What happens next

1. 🤖 Automated checks — build & TypeScript typecheck will run automatically
2. ✅ Vercel preview — a preview deployment will be created (requires maintainer authorization for fork PRs)
3. 👀 Code review — a maintainer will review your changes
4. 🚀 Merge — once approved, your PR will be merged!

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
• ⭐ Star the repo to support the project!

Happy coding! 🎉

[github-actions]

✅ PR Format Check Passed — @srinidhi-2006-bit

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.

[magic-peach]

Hey @srinidhi-2006-bit! This PR has developed merge conflicts with main due to recent merges. Please rebase on main:

git fetch origin
git rebase origin/main
git push --force-with-lease

The changes (live preview aspect ratio update and PrivacyBanner) look good — just need to resolve the conflicts!