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>

releases/manifest.json

@@ -1,27 +1,26 @@
 {
-  "version": "1.7.19-alpha",
+  "version": "1.7.20-alpha",
   "release_date": "2026-04-21",
   "changelog": [
-    "Your node no longer offers a version you've already passed as an 'available update'. If you sideload or skip a release, any stored pointer to an older version is dropped on next restart — the System Update page only offers genuinely newer releases.",
-    "Version comparison is now numeric rather than alphabetic. 1.7.10 correctly outranks 1.7.9 (the old string-order would've got this backwards once patch numbers hit double digits), so update prompts stay accurate past the nines.",
-    "A stale manifest from a slow cache or proxy can no longer downgrade your node. If the manifest reports a version equal to or behind what's running, the node treats that as 'up to date' rather than offering the older version as an update."
+    "Fixed a critical bug where nodes on 'Check & Apply Daily' could end up offline after their nightly update. The scheduler was killing the service a moment too early, before the built-in restart handler could bring the new version back up — leaving the node dead until someone SSH'd in. The scheduler now uses the same restart path as the 'Install Update' button, so auto-applied updates come back online on their own.",
+    "Applies automatically — no action needed on your end beyond taking this update."
   ],
   "components": [
     {
       "name": "archipelago",
-      "current_version": "1.7.18-alpha",
-      "new_version": "1.7.19-alpha",
-      "download_url": "https://git.tx1138.com/lfg2025/archy/raw/branch/main/releases/v1.7.19-alpha/archipelago",
-      "sha256": "c6ffb65ea999c5212e0f93201a9ad77941810c00ea91dfb7397a07358a8a464e",
-      "size_bytes": 40648312
+      "current_version": "1.7.19-alpha",
+      "new_version": "1.7.20-alpha",
+      "download_url": "https://git.tx1138.com/lfg2025/archy/raw/branch/main/releases/v1.7.20-alpha/archipelago",
+      "sha256": "bf4f8b91b021cad445a868f454707e0fa005446f755604f8c3e072bb7a059e6f",
+      "size_bytes": 40640016
     },
     {
-      "name": "archipelago-frontend-1.7.19-alpha.tar.gz",
-      "current_version": "1.7.18-alpha",
-      "new_version": "1.7.19-alpha",
-      "download_url": "https://git.tx1138.com/lfg2025/archy/raw/branch/main/releases/v1.7.19-alpha/archipelago-frontend-1.7.19-alpha.tar.gz",
-      "sha256": "5f70534a3df7012d20ccd8b4134a84a197a082910a9cd45774af249eae9f8d6c",
-      "size_bytes": 162081700
+      "name": "archipelago-frontend-1.7.20-alpha.tar.gz",
+      "current_version": "1.7.19-alpha",
+      "new_version": "1.7.20-alpha",
+      "download_url": "https://git.tx1138.com/lfg2025/archy/raw/branch/main/releases/v1.7.20-alpha/archipelago-frontend-1.7.20-alpha.tar.gz",
+      "sha256": "a82f187b597c51e5f3d8753529914651ab2d8e8bb3ad9c36d287b335e4d386a9",
+      "size_bytes": 162082209
     }
   ]
 }