Tap the card on the charger and the number fills itself in

The enrolment the Anker app does, done here: 0108 a2=7 opens the reader,
0908 brings back the UID. The frames this sends are byte-for-byte the
ones the app was captured sending — checksum included — which is what the
new test asserts.

Adding and removing now write the charger as well as the account: the
device write is the app's own message, the account write is the inferred
one that carries the name, and either may fail without the other.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

API Server/internal/api/integrations_ankersolix.go

@@ -636,6 +636,18 @@ func (s *Server) handleAnkerCardDelete(w http.ResponseWriter, r *http.Request) {
 	})
 }
 
+// POST /api/integrations/anker-solix/chargers/{sn}/rfid-cards/scan — open the
+// charger's card reader and answer with the card someone taps on it. Takes as
+// long as the window does, about twenty seconds, and answers either way: a
+// window that closed with nothing tapped is an answer, not a timeout.
+func (s *Server) handleAnkerCardScan(w http.ResponseWriter, r *http.Request) {
+	who, sn, cfg, ok := s.ankerCardGate(w, r)
+	if !ok {
+		return
+	}
+	s.ankerCardWrite(w, r, who, cfg, "rfid-card-scan", sn, map[string]any{"sn": sn})
+}
+
 // ankerCardGate is everything both writes need before they may run: a caller, a
 // serial, an integration that is on and has credentials, and a rate limit. A
 // gate that is off answers 409 rather than the reads' 200-with-a-reason: a write