feat(OpusEncoder): add opus_decode/encode_float binding

[northwind33]

Closes #171

Description

This PR adds bindings for opus_decode_float and opus_encode_float to support floating-point operations.

• Code changes have been tested, or there are no code changes

[Copilot]

Pull request overview

This PR adds support for floating-point Opus encoding and decoding operations by introducing opus_encode_float and opus_decode_float bindings to the Node.js wrapper.

• Adds encodeFloat and decodeFloat methods to OpusEncoder class
• Allocates a new float* buffer for float operations
• Updates documentation with usage examples for float32 operations

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/node-opus.h	Adds outFloat member variable and declares EncodeFloat and DecodeFloat methods
src/node-opus.cc	Implements float encoding/decoding methods, initializes outFloat buffer in constructor, and registers new methods
README.md	Documents the new float32 encoding/decoding API with usage examples

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[Copilot]

Using delete on an array allocated with new[] is undefined behavior and can cause memory leaks or crashes. Since outFloat is allocated with new float[channels * MAX_FRAME_SIZE] on line 66, it should be deallocated with delete[] instead of delete. The same issue exists with outPcm on line 76.

Suggested change

	if (this->outPcm) delete this->outPcm;
	if (this->outFloat) delete this->outFloat;
	if (this->outPcm) delete[] this->outPcm;
	if (this->outFloat) delete[] this->outFloat;

[Copilot]

Missing error handling for the return value of opus_encode_float. According to the Opus API documentation, opus_encode_float can return negative values on error (same error codes as opus_decode_float). This function should check if compressedLength < 0 and throw an appropriate error, similar to how DecodeFloat checks for negative return values on line 243. Without this check, negative error codes could be passed to Buffer::Copy causing undefined behavior.

Suggested change

	if (compressedLength < 0) {
	Napi::TypeError::New(env, getDecodeError(compressedLength)).ThrowAsJavaScriptException();
	return env.Null();
	}

[northwind33]

I see there are conflicts due to the recent code updates. I'll rebase and fix them shortly.

[northwind33]

Sorry, but I just realized it's 3:00 AM here. I'll fix it later.

[northwind33]

Regarding the remaining points raised by copilot:

• delete vs delete[]: Yes, arrays must be freed with delete[]. However, I realized I simply mirrored the existing logic for outPcm which implies the original code also has this bug as well.
• Error Handling: This also seems correct. I'll add the proper check for them.

I'm ready to push fixes for them. Before I begin, I have some questions; For the two points mentioned above, should I fix the existing bug in this PR while I'm at it? Or would you prefer I only fix my new code and open a separate issue/PR for the existing one?