loggerd: fix audio truncation by processing remaining partial frames

[deanlee]

Fixes an audio truncation issue in the VideoWriter where the last portion of audio data could be lost if it didn't form a complete frame. Previously, any audio samples remaining in the buffer that were fewer than audio_codec_ctx->frame_size would be discarded during cleanup, resulting in truncated audio in the output file.

[adeebshihadeh]

The buffer is so small, does this really make a difference?

[deanlee]

In audio encoding, calling process_remaining_audio() is a standard practice to ensure data integrity, even when using a small buffer.

With AAC encoding at 16 kHz, skipping this step can result in the permanent loss of up to 64 ms of buffered audio. While this may not be noticeable in a single segment, it can introduce small but unwanted gaps between segments, especially when silent video frames appear in those gaps.