feat(ffmpeg): add service worker caching for FFmpeg WASM assets

[deepsikha-dash]

Description

Implemented service worker caching for FFmpeg WASM assets.

Changes made:

• Added public/sw.js service worker
• Cached FFmpeg WASM assets using Cache API
• Registered service worker in src/app/layout.tsx
• Added cache versioning and cleanup of old caches on activation

Benefits:

• FFmpeg WASM files are cached after first download
• Subsequent loads use cached assets
• Reduced repeated network downloads of large FFmpeg WASM files
• Improved performance and loading experience

Closes #181

Type of Contribution

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

Participant Info

• GitHub username: deepsikha-dash
• Contribution level (Beginner/Intermediate/Advanced): Intermediate

Screen Recording

N/A

Recording / Loom link: ## 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 (required for UI/feature/design changes)

[vercel]

@deepsikha-dash 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, @deepsikha-dash!

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 — @deepsikha-dash

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.