docs: fix QUICKSTART - missing default pool/network, tilde-in-arg bug, os-variant

Debian's libvirt-daemon-system doesn't auto-create a default storage
pool (network exists but inactive) - added explicit pool-define/build/
start and net-start steps. Also fixed --cloud-init user-data=~/... not
expanding (tilde only expands at start of a shell word, not after =),
and noted why --os-variant may need to be an older release than the
actual image if osinfo-db is stale.

docs/QUICKSTART.md

@@ -32,16 +32,40 @@ its own pool, rather than pointing at a raw path in `~` — pool operations
 go through libvirtd's API, so it's libvirtd (already running with the
 right privileges) that handles the file ownership, not `k8s` directly.
 
-Make sure everything below targets the system instance — matches where
-Terraform will eventually create the real VMs too:
+Every `virsh`/`virt-install` command below uses `-c qemu:///system` /
+`--connect qemu:///system` explicitly, rather than relying on the
+`LIBVIRT_DEFAULT_URI` env var — for a non-root user that env var is what
+picks system vs. the per-user `qemu:///session` instance, and it's easy for
+it to be set in one terminal and not another, silently causing commands to
+operate on the wrong (session) libvirt instance where nothing you created
+system-side is visible. Explicit `-c` on every command avoids that
+ambiguity entirely.
+
+**Debian's `libvirt-daemon-system` does *not* auto-create a `default`
+storage pool** the way some other distros' packaging does (it does
+auto-create the `default` *network*, just left inactive) — check and fix
+both before doing anything else:
 
 ```sh
-export LIBVIRT_DEFAULT_URI=qemu:///system
+virsh -c qemu:///system pool-list --all
+virsh -c qemu:///system net-list --all
 ```
 
-This only lasts for the current shell — add it to `k8s`'s `~/.bashrc` too
-(`echo 'export LIBVIRT_DEFAULT_URI=qemu:///system' >> ~/.bashrc`) so it's
-still set in step 2 and the teardown section later, even in a fresh login.
+If `pool-list` comes back empty:
+
+```sh
+virsh -c qemu:///system pool-define-as default dir --target /var/lib/libvirt/images
+virsh -c qemu:///system pool-build default
+virsh -c qemu:///system pool-start default
+virsh -c qemu:///system pool-autostart default
+```
+
+If `net-list` shows `default` as `inactive`:
+
+```sh
+virsh -c qemu:///system net-start default
+virsh -c qemu:///system net-autostart default
+```
 
 Download the cloud image somewhere `k8s` can read it — this location
 itself doesn't need to be qemu-readable, since it's only ever read by
@@ -52,18 +76,19 @@ curl -L -o /tmp/noble-base.img \
   https://cloud-images.ubuntu.com/noble/current/noble-server-cloudimg-amd64.img
 ```
 
-Import it into libvirt's `default` storage pool (created automatically
-when `libvirt-daemon-system` was installed in step 1), then create a
-copy-on-write overlay on top of it, sized up to 20G:
+Import it into the `default` pool, then create a copy-on-write overlay on
+top of it, sized up to 20G:
 
 ```sh
-virsh vol-create-as default k3s-manual-base.qcow2 \
+virsh -c qemu:///system vol-create-as default k3s-manual-base.qcow2 \
   --capacity "$(stat -c%s /tmp/noble-base.img)" --format qcow2
-virsh vol-upload --pool default k3s-manual-base.qcow2 /tmp/noble-base.img --sparse
+virsh -c qemu:///system vol-upload --pool default k3s-manual-base.qcow2 /tmp/noble-base.img --sparse
 rm /tmp/noble-base.img
 
-virsh vol-create-as default k3s-manual.qcow2 20G --format qcow2 \
+virsh -c qemu:///system vol-create-as default k3s-manual.qcow2 20G --format qcow2 \
   --backing-vol k3s-manual-base.qcow2 --backing-vol-format qcow2
+
+virsh -c qemu:///system vol-list --pool default   # should list both volumes
 ```
 
 Write the cloud-init user-data — paste in the contents of
@@ -103,18 +128,30 @@ usable cluster.
 
 The cloud-init user-data file itself is fine living under `~/vms` — unlike
 the disk, it's only ever read client-side by `virt-install` (as `k8s`),
-which then hands the rendered seed data to libvirtd over the API:
+which then hands the rendered seed data to libvirtd over the API. Note
+`$HOME` rather than `~` in the `--cloud-init` argument below — `~` only
+expands at the start of a shell word, not after `=` inside one, so
+`user-data=~/vms/...` would be passed to virt-install literally with the
+tilde still in it.
+
+`--os-variant ubuntu22.04` below is deliberately not `ubuntu24.04` (the
+actual image) — `osinfo-db` on Debian 12 may not recognize the newer
+variant name yet. Check what yours knows about with
+`osinfo-query os | grep -i ubuntu`; the hint mostly just tunes libvirt's
+domain defaults (virtio devices, clock, etc.), so a close-enough variant
+against a cloud-init `--import` like this is harmless:
 
 ```sh
 virt-install \
+  --connect qemu:///system \
   --name k3s-manual \
   --memory 2048 \
   --vcpus 2 \
   --disk vol=default/k3s-manual.qcow2 \
   --import \
-  --os-variant ubuntu24.04 \
+  --os-variant ubuntu22.04 \
   --network network=default \
-  --cloud-init user-data=~/vms/k3s-manual-user-data.yaml \
+  --cloud-init user-data=$HOME/vms/k3s-manual-user-data.yaml \
   --graphics none \
   --noautoconsole
 ```
@@ -124,7 +161,7 @@ virt-install \
 Give cloud-init ~2 minutes to finish installing k3s after the VM boots.
 
 ```sh
-virsh domifaddr k3s-manual   # note the IP under the default network
+virsh -c qemu:///system domifaddr k3s-manual   # note the IP under the default network
 
 ssh k3s@<VM_IP> sudo cat /etc/rancher/k3s/k3s.yaml \
   | sed "s/127.0.0.1/<VM_IP>/" > ~/.kube/config-manual