fix: channel PSK validation

app/src/main/java/com/geeksville/mesh/ui/components/config/EditChannelDialog.kt

@@ -98,7 +98,8 @@ fun EditChannelDialog(
                             try {
                                 pskString = it // empty (no crypto), 128 or 256 bit only
                                 val decoded = Base64.decode(it, base64Flags).toByteString()
-                                if (decoded.size() in setOf(0, 16, 32)) pskInput = decoded
+                                val fullPsk = Channel(channelSettings { psk = decoded }).psk
+                                if (fullPsk.size() in setOf(0, 16, 32)) pskInput = decoded
                             } catch (ex: Throwable) {
                                 // Base64 decode failed, pskError true
                             }