fix(ffi): reject invalid SoxResampler parameters at creation

[RaphaelFakhri]

Summary

SoxResampler accepted parameters that soxr cannot resample with and returned a resampler that failed later. This change validates them at creation and returns an error instead.

• A zero, negative or non-finite input or output rate created a resampler. The first push then panicked (verified for a zero input rate).
• Zero channels created a resampler. The first push panicked on an integer division by zero.
• soxr_create was called with a null error pointer, so a creation failure was never reported and only produced a null soxr_t.

Because these run behind the FFI boundary, a bad value passed from an SDK such as AudioResampler(input_rate=0, ...) aborts the host process instead of raising an error.

Changes

• Reject non-finite or non-positive sample rates and zero channels in SoxResamplerInner::new.
• Pass a real error out-parameter to soxr_create and return its message. A null result without a message returns a generic error.
• Add invalid_parameters_are_rejected to the resampler tests.
• Add a livekit-ffi patch changeset.

Testing

cargo test -p livekit-ffi --lib resampler

• Before the fix, invalid_parameters_are_rejected fails and the other resampler tests pass (7 passed, 1 failed).
• After the fix, all resampler tests pass (8 passed).
• cargo fmt -p livekit-ffi -- --check reports no changes.

[CLAassistant]

All committers have signed the CLA.

[RaphaelFakhri]

Valid finding, fixed in the new commit. SoxResamplerInner::new now also checks that both input_rate / output_rate and output_rate / input_rate are finite and greater than zero, and returns the constructor error otherwise. Rates such as input_rate=1e-320 with output_rate=16000 are rejected at creation instead of panicking on the first push. The invalid_parameters_are_rejected test now covers the underflow and overflow cases.

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