Evaluate if Brotli file variants are still needed

## Context

During the upload step in `consumer-server/src/logic/conversion-task.ts`, all converted asset bundles are uploaded with both `Brotli` and `Uncompressed` variants. This doubles the number of files stored in S3.

## Question

Is the Brotli variant still needed? Cloudflare and most CDNs can handle compression at the edge, so pre-compressing and storing `.br` files may be redundant overhead in both storage and conversion time.

## Action items
- [ ] Check if the explorer client (WebGL/desktop) explicitly requests `.br` files or relies on CDN `Accept-Encoding` negotiation
- [ ] Measure storage cost impact of removing Brotli variants
- [ ] If not needed, remove `FileVariant.Brotli` from the upload matches and clean up related code

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