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/api.ts

@@ -350,6 +350,24 @@ export function testAnpr(driverId: string, config: DeviceConfig): Promise<AnprTe
   });
 }
 
+/** Result of a physical print test: a real test slip is pushed to the printer. */
+export type PrintTestResult =
+  | { ok: true; tookMs: number }
+  | { ok: false; reason: string; detail?: string; tookMs?: number };
+
+/** Print a real test slip on the printer — without saving. Confirms the printer
+ *  actually feeds paper + fires the head (healthCheck only opens the transport). */
+export function testPrint(
+  driverId: string,
+  config: DeviceConfig,
+  id?: string,
+): Promise<PrintTestResult> {
+  return apiFetch<PrintTestResult>("/api/setup/test-print", {
+    method: "POST",
+    body: JSON.stringify({ driverId, config, id }),
+  });
+}
+
 // --- Admin reports -------------------------------------------------------
 export type ReportBucket = "hour" | "day" | "month";