Shadow-mode client script and cutover doc correction

CHANGELOG.md

@@ -79,6 +79,33 @@ each fix ships with the check, report or document that would have surfaced it.
 
 ### Fixed
 
+- The toner forecast was reading the wrong end of the window. Zabbix applies a
+  query's `limit` to the whole answer rather than to each item, and combined
+  with an ascending sort that kept the OLDEST rows: a four-cartridge printer
+  polled every five minutes writes over 100k readings in 90 days, so a "90 day"
+  forecast was fitted to the first few days of the window and nothing since.
+  That is where "4 days left" beside a cartridge at 20% came from - the rate
+  was real, it just described a cartridge thrown away in May. Long windows now
+  read hourly trends, which is the table meant for this and is a tenth of the
+  rows; short ones read raw history, newest first, with a budget scaled per
+  item.
+- The forecast now counts down from the level it displays. It showed the live
+  reading but computed days-left from the last stored one, so the two could
+  disagree by a whole cartridge. A live level far above the stored run is
+  treated as a swap that happened since the last reading rather than as a
+  collapse in the burn rate.
+- A cartridge at or below 5% reads as empty rather than as a slow drain. At 1%
+  losing a tenth of a point a day the arithmetic said ten days; the printer is
+  out of toner, and it is the first thing that should be ordered.
+- Days-left in the forecast is per cartridge again. It was rendered in a cell
+  spanning the printer's rows, which put the printer's soonest figure beside
+  every supply it had - a cartridge at 20% displaying "4 days" that belonged to
+  the black beside it, and a cartridge at 1% displaying weeks that belonged to
+  nothing on that row at all.
+- Supplies typed as floats were dropped from the forecast on any printer that
+  also had an integer-typed one. The two live in different Zabbix history
+  tables and the fetch stopped at whichever answered first, so half a printer's
+  cartridges silently had no history at all.
 - A shop-floor PC that reported the machine number of a machine ShopDB already
   knew got a 500 from the collector, on every report, forever. The reported
   machine number was being written to the PC's own `assets.assetnumber`, which