add disk encryption check

client/system/disk_encryption_stub.go

@@ -0,0 +1,10 @@
+//go:build android || ios || freebsd || js
+
+package system
+
+import "context"
+
+// detectDiskEncryption is a stub for unsupported platforms.
+func detectDiskEncryption(_ context.Context) DiskEncryptionInfo {
+	return DiskEncryptionInfo{}
+}