[4.0] Offline installer ISO missing xfsprogs package preventing XFS filesystem during installation

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**Azure Linux version**
Azure Linux 4.0

**Deployment / platform**
KVM VM (PXE network boot, offline installer)

**Is your feature request related to a problem? Please describe.**
When installing Azure Linux 4 using the offline installer ISO with a custom kickstart, I cannot use XFS as the root filesystem. The offline repo bundled in the ISO (`/opt/azl-offline-repo/`) does not include `xfsprogs`, so `mkfs.xfs` is unavailable during installation. Anaconda fails if the kickstart specifies `--fstype=xfs.`
The kernel has XFS support compiled as a module (`xfs.ko.xz` is present), and `xfsprogs` is available in the upstream repo (`azurelinux-base`), but during offline installation there's no network access to fetch it.

**Describe the solution you'd like**
Include `xfsprogs` and its dependencies `inih` and `userspace-rcu` in the offline installer repo so that XFS can be used as a filesystem option during installation, same as ext4.

**Describe alternatives you've considered**
Using ext4 instead. Works fine, but XFS is the standard for RHEL-based environments and many enterprise workloads expect it. Having it available during offline install would make Azure Linux more flexible as a drop-in for those environments.

**Additional context**
The offline repo has around 410 packages covering the base system. Adding `xfsprogs` and its dependencies (`inih`, `userspace-rcu`) totals ~1.4 MB and would enable XFS support without meaningful impact on ISO size. The kernel module is already shipped, just the userspace tooling is missing from the offline bundle.

Inspect the offline repository at /opt/azl-offline-repo/ and determine how its package contents are assembled. Confirm that xfsprogs and its dependencies, inih and userspace-rcu, are included, then verify that a custom kickstart using --fstype=xfs succeeds without network access.

Written by the indexing model from the issue text.