Resolve a driver by vendor, and converge a bay's printers from ShopDB

Two rows now cover 41 of 44 printers. printerdrivers could only bind a driver to
ONE modelnumberid, so the HP and Xerox universal drivers - which between them
cover almost the whole floor - would have needed 21 near-duplicate rows pointing
at the same package. That is a table nobody keeps true, and it is why 42 of 44
printers resolved no driver at all.

printerdrivers gains vendorid, and resolution runs most-specific-first: the
printer's model, then its vendor, then the pre-vendorid convention of matching
the vendor word in the driver's name so a site that populated the table before
the column existed does not silently lose every driver on upgrade. A row that
names a vendor is never matched by its text, because a mis-set vendor resolving
to the wrong package is worse than resolving to none.

Six rows now resolve 44 of 44 printers at the reference site, and the DesignJet
correctly takes its own driver over the HP universal one.

Set-ShopdbPrinters.ps1 is the client half: ask for-host, create the queues that
are missing, record the desired default. It NEVER removes a queue - a bad minute
from the API must not take printers away from a working bay - and it never
fetches a driver, because downloading 48 MB while somebody waits to print is the
wrong moment. The common scope stages those.

Apply-ShopdbDefaultPrinter.ps1 applies the default in the USER's context, which
is the only context that can: SYSTEM cannot set a per-user default for somebody
else. It also turns off "Let Windows manage my default printer", without which
Windows silently overwrites the choice the next time anyone prints elsewhere -
a fix that undoes itself within a day.

VALIDATED ON WINDOWS 11 AGAINST A LIVE SHOPDB, not only by tests. Printers were
assigned to a MACHINE; a PC controlling it, holding no rows of its own, created
both queues bound to the right universal drivers, recorded the default and set
it, and a second run changed nothing. The first attempt failed with
"Relationship types are not seeded - run: flask seed reference-data", which is
the deployment trap the plan predicted, caught by an explicit error rather than
silently resolving nothing.

plugins/printers/client/DEPLOYING-DRIVERS.md

@@ -112,3 +112,33 @@ reference site's fleet:
 | `ZDesigner ZT411-300dpi ZPL` | Zebra ZT411 labels |
 | `EPSON TM-C3500` | Epson ColorWorks labels |
 | `DTC4500e Card Printer` | HID FARGO card printer |
+
+## The other half: assigning printers
+
+Staging drivers is only delivery. `Set-ShopdbPrinters.ps1` is what makes a bay's
+queues match ShopDB, and `Apply-ShopdbDefaultPrinter.ps1` applies the default in
+the user's context. Two manifest entries, both `DetectionMethod: Always`:
+
+```json
+{
+  "_comment": "Create the queues this bay is assigned. Converges: existing queues are left alone, and nothing is ever removed.",
+  "Name": "ShopDB printers",
+  "Type": "PS1",
+  "Script": "scripts/Set-ShopdbPrinters.ps1",
+  "DetectionMethod": "Always"
+}
+```
+
+The default printer is per-user, so SYSTEM cannot set it for the person logged
+on. `Set-ShopdbPrinters.ps1` records it in `HKLM:\SOFTWARE\GE\ShopDB`
+`DefaultPrinter`, and `Apply-ShopdbDefaultPrinter.ps1` runs as the user - at
+logon, and on a repeat if the site wants drift corrected.
+
+Order matters on a new bay: drivers, then queues, then the default. Each step is
+a no-op once satisfied, so running all three every cycle costs a few registry
+reads.
+
+Verified end to end on Windows 11 against a live ShopDB: printers assigned to a
+MACHINE, a PC controlling it and holding no rows of its own, and the bay created
+both queues with the right universal driver, recorded the default, and set it -
+then a second run changed nothing.