Audio Channel ConverterConvert audio between mono and stereo channel configurations.

For stereo-to-mono conversion, the tool reads both channels from the AudioBuffer and mixes them: monoSample = (leftSample + rightSample) / 2. A new single-channel AudioBuffer is created with the averaged samples. For mono-to-stereo conversion, the single channel's data is copied to both the left and right channels of a new two-channel AudioBuffer. The tool can also extract individual channels: left-only or right-only from stereo. An OfflineAudioContext handles the channel mapping using ChannelSplitterNode (to separate channels) and ChannelMergerNode (to combine them). The output maintains the original sample rate and bit depth. The resulting audio is encoded as a WAV file with the appropriate channel count in the fmt header.