feat(setup): print a real test slip from the printer "Test connection" modal

healthCheck only opens the transport (TCP connect / USB open) — it proves the
printer is REACHABLE, not that paper feeds and the head fires. Add a "Print test
slip" action so the admin can physically confirm a printer is live (the new
host-net USB /dev/usb/lpN path, or a network printer).

- server: POST /api/setup/test-print — printer-only, re-merges stored secrets like
  /test (so an edited network printer authenticates), creates the device, and pushes
  a short slip via the device-agnostic printReport(). Fail-soft: a print error
  (paper out, head fault, transport drop) is reported, never a 500. Mirrors the
  test-anpr pattern.
- web: testPrint() client + PrintTestResult; a button in the device modal shown for
  category=printer, with ok/fail rendering. i18n keys in sq + en (parity holds).

Server 168 tests pass; web + server typecheck clean.

Claude-Session: https://claude.ai/code/session_01Xcm6ikLgGoCxxHrxtjkk5V

apps/web/src/lib/i18n/en.ts

@@ -406,6 +406,13 @@ export const en: Catalog = {
     "anprFail.vision-disabled": "Vision service is disabled — enable it (VISION_ENABLED) to test ANPR.",
     "anprFail.snapshot-failed": "Couldn't take a snapshot from the camera (offline or unreachable).",
     "anprFail.no-plate": "No plate found in the snapshot.",
+    // Printer test slip — pushes a real slip so the admin can confirm it physically prints.
+    testPrint: "Print test slip",
+    printTesting: "Printing…",
+    testPrintHint:
+      "Sends a test slip to the printer now. ‘Connected’ only opens the link — this confirms the printer actually feeds paper.",
+    printOk: "✓ Test slip sent ({{ms}} ms). Check the printer.",
+    "printFail.print-failed": "The printer rejected the job (out of paper, cover open, or the link dropped).",
     alarmUrlTitle: "Alarm Server settings (enter these in the camera)",
     alarmUrlHint:
       "Enter these in the camera at Configuration → Event → … → Alarm Settings (or Notify Surveillance Center). The camera POSTs every event here — no polling.",