M1.4: Create Cloudflare R2 bucket and bind download.zurvanlinux.org

[mshafiee]

Acceptance criteria

• R2 bucket created and public access enabled
• download.zurvanlinux.org bound to bucket as Cloudflare custom domain
• GitHub Actions secrets added:
  • R2_ACCESS_KEY_ID
  • R2_SECRET_ACCESS_KEY
  • R2_ENDPOINT
  • R2_BUCKET
• ISO upload path in build-iso.yml verified end-to-end

Dependencies

• Cloudflare account access
• R2 API token (Object Read & Write)

Notes

R2 egress is free; ISO binaries stream from origin and are not edge-cached above 512 MB.