release(v1.7.20-alpha): stop auto-apply scheduler killing the service

The 3AM auto-update path called std::process::exit(0) immediately
after apply_update returned. apply_update had already spawned a 2s-
delayed systemctl restart, but exit(0) killed the runtime before that
spawned task could run — and the unit's Restart=on-failure does not
trigger on a clean exit 0, so the service stayed dead until someone
SSH'd in and started it manually (.253 hit this today).

Scheduler now returns from the task without killing the process;
apply_update's existing restart path (same one the UI's Install
Update button uses) brings the new version up cleanly.

Also hardens the ISO CI: the AIUI inclusion step now falls back to
extracting from the newest release tarball if the runner's cached
/opt/archipelago/web-ui/aiui path is missing, so a reprovisioned
runner can't silently ship a frontend tarball without AIUI. The ISO
build step also sanity-checks the binary exists before invoking the
builder.

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

neode-ui/src/views/settings/AccountInfoSection.vue

@@ -180,6 +180,17 @@ init()
               </button>
             </div>
             <div class="overflow-y-auto flex-1 min-h-0 space-y-6 pr-1">
+              <!-- v1.7.20-alpha -->
+              <div>
+                <div class="flex items-center gap-2 mb-3">
+                  <span class="text-xs font-mono px-2 py-0.5 rounded bg-orange-500/20 text-orange-300">v1.7.20-alpha</span>
+                  <span class="text-xs text-white/40">Apr 21, 2026</span>
+                </div>
+                <div class="space-y-3 text-sm text-white/80 pl-3 border-l border-white/10">
+                  <p>Fixed a critical bug where nodes on the automatic daily-update schedule could end up offline after their nightly update. The scheduler was killing the service a moment too early, before the built-in restart handler had a chance to bring the new version back up — leaving the node dead until someone SSH'd in and started it manually. The scheduler now hands off cleanly to the same restart path the 'Install Update' button uses, so auto-applied updates come back online on their own.</p>
+                  <p>Applies to any node configured for 'Check &amp; Apply Daily' — no change required on your end, the fix ships with this update.</p>
+                </div>
+              </div>
               <!-- v1.7.19-alpha -->
               <div>
                 <div class="flex items-center gap-2 mb-3">