ci: install systemd-ukify so mkosi's Bootable=yes step succeeds

mkosi refused with "Could not find 'ukify'". The live image's mkosi.conf
sets Bootable=yes, and mkosi invokes ukify to package the Unified
Kernel Image alongside vmlinuz+initrd.img. On Debian/Ubuntu, ukify
ships in the `systemd-ukify` apt package (not in `systemd`).

Added to both release.yml and e2e.yml's live-image dep lists.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.gitea/workflows/e2e.yml

@@ -36,7 +36,8 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends \
-            mkosi debootstrap squashfs-tools qemu-system-x86 qemu-utils \
+            mkosi debootstrap squashfs-tools systemd-ukify \
+            qemu-system-x86 qemu-utils \
             dnsmasq iperf3 ipxe-qemu
 
       - name: Install templ

.gitea/workflows/release.yml

@@ -33,7 +33,7 @@ jobs:
         run: |
           sudo apt-get update
           sudo apt-get install -y --no-install-recommends \
-            mkosi debootstrap squashfs-tools dosfstools
+            mkosi debootstrap squashfs-tools dosfstools systemd-ukify
 
       - name: Install templ
         run: go install github.com/a-h/templ/cmd/templ@v0.3.1001