fix(a2l): normalise AMS Lite unit 16->6 so slots load and deduct (#a2l-am-unit-16)

The A2L reports its 4-slot AMS Lite as unit id 16, but its slot-presence
bitmasks sit at bit base 24 (id 6) and it reports tray_now as a local 0-3
slot. Fed the raw id 16, the ams_id*4+slot convention probed bits 64-67
(always zero) and marked loaded slots empty; the local tray_now was read as
global, so usage deducted from the wrong spool (or not at all); and the
ams_id<=7 DB constraint rejected id-16 Spoolman links.

Normalise the Lite 16->6 at the MQTT ingest boundary so global tray ids land
at 24-27 - matching the firmware's own bit base, working with every existing
ams_id*4+slot consumer, colliding with nothing, and passing the DB
constraint. Globalise tray_now to 24+slot, widen the valid-tray guards, label
the unit "AMS Lite", and build the confirmed ams_mapping2 {ams_id:16,
slot_id:0-3} / flat 0-3 for dispatch. Outbound slot commands translate 6->16
on the wire via a single helper. Self-scoping: only unit id 16 is touched, so
all other printers/AMS types are unaffected. One uncaptured wire field (the
physical global tray on load/cali) is extrapolated and isolated to the helper.

static/index.html

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-    <script type="module" crossorigin src="/assets/index-4hVOt7rj.js"></script>
+    <script type="module" crossorigin src="/assets/index-DCk9Jev0.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-CKAbipPc.css">
   </head>
   <body>