Prepare Release

[github-actions]

This PR is a preview of the release that release-plan has prepared. To release you should just merge this PR 👍

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Release (2026-09-11)

• ember-cli-fastboot 6.0.0 (major)
• fastboot 6.0.0 (major)
• fastboot-app-server 5.0.3 (patch)
• fastboot-express-middleware 5.0.2 (patch)

💥 Breaking Change

• ember-cli-fastboot
  • #988 remove very old code to support ember < 2.10 (@mansona)
• fastboot
  • #956 Update the default sandbox (@NullVoxPopuli)
• Other
  • #987 Drop support for Ember < 3.28 (@mansona)

🚀 Enhancement

• ember-cli-fastboot
  • #986 move experimental-render-mode-rehydrate setup to a real initializer (@mansona)

🏠 Internal

• Other
  • #983 re-enable release scenario (@mansona)
  • #985 update ember-cli versions in scenarios (@mansona)
  • #982 add a basic render rehydrate test (@mansona)
• fastboot
  • #981 remove unused fastboot fixtures (@mansona)

Committers: 2

• Chris Manson (@mansona)
• @NullVoxPopuli