Own printers, driverless only

The fourth panel this desktop handed to GNOME Settings, and the last one
worth owning.

Driverless only, deliberately. Adding a printer that describes its own
capabilities over IPP is supported; choosing a PPD or fetching a vendor
driver is not, and the page says so rather than pretending. That
restraint is the whole design: a wrong driver produces a printer that
accepts jobs, reports success, and prints nothing, which is the worst
failure this page could ship because it looks like it worked. A printer
old enough to need a PPD stays a job for the system printer tool.

Printers and the queue are separate cards because they answer separate
questions. Which printers exist is one; where a document went is the
other, and it is the one that actually brings someone here -- so the
queue is a single list across every printer.

Device URIs are validated by scheme before reaching CUPS, whose backends
run as root. file: and pipe: do not lead to a printer and are refused
here rather than further down.

This machine has no printer, so the page was built against a temporary
CUPS queue that was created, exercised through the service, and removed;
the service was confirmed to observe the removal rather than merely
perform it. Discovery and the driverless add path are verified by their
refusals rather than against hardware.

Claude-Session: https://claude.ai/code/session_01BRvzt4H8XXLPVH5MyYdk9L

config/dot/quickshell/modules/settings/SettingsShell.qml

@@ -123,6 +123,7 @@ Rectangle {
             case "storage": return storagePage;
             case "users": return usersPage;
             case "sharing": return sharingPage;
+            case "printers": return printersPage;
             case "services": return healthPage;
             case "about": return aboutPage;
             default: return homePage;
@@ -164,6 +165,7 @@ Rectangle {
     Component { id: storagePage; StoragePage {} }
     Component { id: usersPage; UsersPage {} }
     Component { id: sharingPage; SharingPage {} }
+    Component { id: printersPage; PrintersPage {} }
     Component { id: accessibilityPage; AccessibilityPage {} }
     Component { id: powerPage; PowerPage {} }
     Component { id: dateTimePage; DateTimePage {} }