fix: handle expected BLE disconnect after SaveConfig command

The DX-Smart CP28 beacon reboots after receiving SaveConfig (0x60) to
persist config to flash. This drops the BLE connection before the write
callback fires, causing the app to report "Unexpected disconnect" even
though the config was successfully saved.

Now we check if we're on the last command (SaveConfig) when disconnect
occurs — if so, treat it as success instead of failure.

Co-Authored-By: Luna <luna@payfrit.com>

PayfritBeacon/BeaconProvisioner.swift

@@ -974,6 +974,11 @@ extension BeaconProvisioner: CBCentralManagerDelegate {
         } else if state != .success && state != .idle {
             if case .failed = state {
                 // Already failed
+            } else if state == .writing && dxSmartWriteIndex >= dxSmartCommandQueue.count - 1 {
+                // SaveConfig (last command) was sent — beacon rebooted to apply config
+                // This is expected behavior, treat as success
+                DebugLog.shared.log("BLE: Disconnect after SaveConfig — treating as success")
+                succeed()
             } else {
                 fail("Unexpected disconnect", code: .disconnected)
             }