feat(changelog): file-storage-added-file-storage-is-now-in-general-avail 2026-07-16 (#6699)

* feat(changelog): add new entry

* Update changelog/july2026/2026-07-16-file-storage-added-file-storage-is-now-in-general-avail.mdx

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Co-authored-by: Changelog bot <changelog-bot@users.noreply.github.com>
Co-authored-by: Firdevs Arslan <farslan@scaleway.com>