fix(update): concurrent apply reads as progress, not failure; idle-IO extraction

"Another update operation is already running" surfaced as a scary
failure while the update was in fact applying fine (OptiPlex, v1.7.118
rollout). The apply path now joins the in-flight install — same
overlay, same wait-for-new-version polling — and a concurrent download
attempt shows a calm in-progress note (EN+ES strings added). The
backend's tarball extractions run under ionice -c3 nice -n10 so a
200MB update can't starve podman/status calls into multi-minute
timeouts on small disks.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/Cargo.lock

@@ -104,7 +104,7 @@ dependencies = [
 
 [[package]]
 name = "archipelago"
-version = "1.7.117-alpha"
+version = "1.7.118-alpha"
 dependencies = [
  "anyhow",
  "archipelago-container",