fix(ci): apk-install smoke prerequisites before running smoke-vm.sh

The Forgejo runner container is Alpine with a near-empty base — no
curl, python3, arp-scan, or sudo out of the box. scripts/smoke-vm.sh
needs all four:
  - curl: every PVE API call
  - python3: JSON parsing of PVE responses
  - arp-scan: MAC→IP discovery on the LAN (live ISO has no guest agent)
  - sudo: so the same script also works from a dev laptop as non-root

Without this step the smoke job fails immediately on "curl: not found",
regardless of whether the PVE secrets are correctly set.

Added to both build-iso.yml (inline smoke after ISO build) and
smoke-latest.yml (workflow_dispatch retest path).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

.forgejo/workflows/build-iso.yml

@@ -62,6 +62,13 @@ jobs:
           cp -f "$iso" /data/smoke-cache/latest.iso
           ls -lh /data/smoke-cache/latest.iso
 
+      - name: Install smoke prerequisites
+        # Runner container is Alpine with a near-empty base; smoke-vm.sh
+        # needs curl, python3, arp-scan, and sudo (kept so the script
+        # also works when invoked from a dev laptop as a non-root user).
+        # apk cache survives across jobs so subsequent runs are ~1 s.
+        run: apk add --no-cache curl python3 arp-scan sudo
+
       - name: Smoke-test ISO on Proxmox test host
         # Inlined as a step (rather than a separate job with `needs:`) so
         # we can reuse the ISO that's already in the workspace — Forgejo's

.forgejo/workflows/smoke-latest.yml

@@ -33,6 +33,12 @@ jobs:
           echo "Will smoke: $iso"
           ls -lh "$iso"
 
+      - name: Install smoke prerequisites
+        # Runner container is Alpine with a near-empty base; smoke-vm.sh
+        # needs curl, python3, arp-scan, and sudo (kept so the script
+        # also works when invoked from a dev laptop as a non-root user).
+        run: apk add --no-cache curl python3 arp-scan sudo
+
       - name: Smoke-test ISO on Proxmox test host
         env:
           PVE_TEST_HOST: ${{ secrets.PVE_TEST_HOST }}