method encryptFile() has bug

```
private fun encryptFile() {
val title = binding.titleEditText.text.toString()
val body = binding.bodyEditText.text.toString()

if (title.isBlank()) return

try {
deleteFile(existingFileTitle)
val encryptedFile = getEncryptedFile(title)
encryptedFile.openFileOutput().use { output ->
output.write(body.toByteArray())
}
} catch (e: Exception) {
e.printStackTrace()
showSnackbar(R.string.error_unable_to_save_file)
}
}
```

should change deleteFile(existingFileTitle) to deleteFile(title )

Locate encryptFile() in the Android sample and inspect the surrounding save or rename flow. Verify the deletion call against the title used to create the encrypted file, then exercise saving an edited file to confirm the obsolete file is removed and the new file remains.

Written by the indexing model from the issue text.