QR: add type-to-confirm delete on the QR code page

Users asked to delete codes they no longer need. Add a destroy route +
controller action (authorized via QrCodePolicy::delete) and a danger-zone
delete on the show page behind a confirmation modal that requires typing the
code's label — deliberately not a one-click delete since it permanently
breaks the printed code and removes its scan history.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/Http/Controllers/Qr/QrCodeController.php

@@ -279,6 +279,20 @@ class QrCodeController extends Controller
         return back()->with('success', 'QR code updated.');
     }
 
+    public function destroy(Request $request, QrCode $qrCode): RedirectResponse
+    {
+        $this->authorize('delete', $qrCode);
+
+        // Remove the code and its scan history. Deletion is gated behind a
+        // type-to-confirm dialog in the UI — this is intentionally permanent.
+        $qrCode->scans()->delete();
+        $qrCode->delete();
+
+        return redirect()
+            ->route('user.qr-codes.index')
+            ->with('success', 'QR code deleted.');
+    }
+
     public function stylePreview(Request $request): Response
     {
         $validated = $request->validate(array_merge($this->styleRules(), [