fix(update): 30-min download timeout + tidier progress number

Follow-up to 56d4875b, same v1.7.0-alpha shipping band.

Backend download timeout bumped from 300s to 1800s (update.rs) with an
explicit 30s connect timeout. git.tx1138.com raw-file throughput can sit
around 70–80 KB/s, which meant OTA downloads were timing out at ~55%
through the 40 MB binary even though the SHA would have matched on a
full pull. 30 min gives ample headroom for the worst LAN-to-VPS link we
actually hit.

Frontend: SystemUpdate.vue now formats downloadPercent with toFixed(2)
via a new computed, so the progress card shows "45.23%" instead of
"45.270894%". Cosmetic only; the underlying ref still tracks raw floats.

Manifest changelog rewritten in user-facing language per the saved
feedback — no file paths, function names, or "root cause" phrasing.

Artifacts refreshed:
  binary   d85a71c5…982f4  40360936
  frontend 8adcdacf…e687f6 76986852

ISO at image-recipe/results/archipelago-installer-unbundled-x86_64.iso
(Apr 20 09:00) carries both fixes for fresh installs.

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

neode-ui/src/views/SystemUpdate.vue

@@ -110,10 +110,10 @@
       <div class="w-full h-3 bg-white/10 rounded-full overflow-hidden mb-2">
         <div
           class="h-full bg-orange-400 rounded-full transition-all duration-500"
-          :style="{ width: downloadPercent + '%' }"
+          :style="{ width: downloadPercentFormatted + '%' }"
         ></div>
       </div>
-      <p class="text-xs text-white/60">{{ t('systemUpdate.percentComplete', { percent: downloadPercent }) }}</p>
+      <p class="text-xs text-white/60">{{ t('systemUpdate.percentComplete', { percent: downloadPercentFormatted }) }}</p>
     </div>
 
     <!-- Applying -->
@@ -254,6 +254,7 @@ const updateInProgress = ref(false)
 const statusMessage = ref('')
 const statusIsError = ref(false)
 const downloadPercent = ref(0)
+const downloadPercentFormatted = computed(() => downloadPercent.value.toFixed(2))
 
 const lastCheckDisplay = computed(() => {
   if (!lastCheck.value) return t('common.never')