Fix per-job queue ETA showing for jobs that cannot start now

The scheduler only writes waiting_reason on the model-based assignment
path, so a job pinned to a specific printer sits behind a running print
with no marker at all. Every such job rendered an identical "starts now"
ETA that was wrong by the length of everything ahead of it.

Decide eligibility on the page instead: an item gets an ETA only when its
printer is idle and it is the item the scheduler would dispatch next,
following the same ordering the scheduler uses. Staged and future-
scheduled items do not block the item behind them, matching the
scheduler, and items conditional on a previous print are excluded.

The value also froze at first render, since react-query's structural
sharing keeps the queue reference stable and nothing re-rendered the row.
formatETA now accepts a base instant and the page drives it from a 30s
clock shared by every visible row.

Retire the borrowed printers.estimatedCompletion tooltip for a queue key
that says what the number means, translated into all 13 locales.

static/index.html

@@ -26,7 +26,7 @@
 
     <!-- Splash screens for iOS -->
     <link rel="apple-touch-startup-image" href="/img/android-chrome-512x512.png" />
-    <script type="module" crossorigin src="/assets/index-CCCWDEkl.js"></script>
+    <script type="module" crossorigin src="/assets/index-DPZgvI9N.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-C_6BSgrK.css">
   </head>
   <body>