Fix audio processing when saving

[Myzel394]

Related to #112

Update the saveRecording function in RecorderEventsHandler.kt to handle the case where there is only one batch and skip processing.

• Add a check to see if there is only one batch and skip concatenation if true.
• Modify the saveRecording function to use the single batch file path if there is only one batch.
• Update the saveAudioFile and saveVideoFile calls to use the single batch file path if there is only one batch.

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