PitchShift: Fix streaming silence when reset=False

[codyjhsieh]

Fixes #415.

Three interacting bugs cause PitchShift to produce all-zero output when processing audio in streaming mode (reset=False). A single-shot call with reset=True works correctly, but any streaming use — voice chat, DJ apps, chunked file processing — gets permanent silence.

Problem

1. PrimeWithSilence::prepare() clears the delay line buffer on every call. It calls JUCE's setMaximumDelayInSamples() unconditionally, which internally calls reset() → bufferData.clear(). Since processFloat32 calls prepare() before every process(), the 44100-sample delay line loses all stored audio between streaming calls. The pitch shifter only ever receives silence as input.

2. RubberbandPlugin::getLatencyHint() ratchets upward via std::max. The initialSamplesRequired member variable can only grow, inflating the latency estimate on each call. The pipeline uses this to decide how many output samples to trim.

3. processFloat32 trims output by latency even in streaming mode. When reset=False, the pipeline passes isProbablyLastProcessCall=false, so it never extends the buffer to accommodate latency. The latency trimming then reduces the output to a zero-length array.

Solution

• PrimeWithSilence.h: Guard setMaximumDelayInSamples() with a check — only call it when the value actually changes. This preserves the delay buffer across streaming calls.
• RubberbandPlugin.h: Replace the ratcheting getLatencyHint() with a constant: rbPtr->getLatency() + lastSpec.maximumBlockSize. Remove the initialSamplesRequired member.
• process.h: In streaming mode (reset=False), set totalOutputLatencySamples = 0 so the full buffer is returned, including any leading silence from plugin priming.

Result

• Streaming produces audio after the expected ~46500-sample priming period at all chunk sizes (512, 2048, 4096, 8192, 44100, 88200).
• Single-shot reset=True latency compensation is unchanged (PitchShift(0) identity error < 1e-6).
• All existing tests pass (pitch shift, priming, latency compensation, time stretch).
• Added streaming tests covering multiple chunk sizes, sample rates, and reset-then-stream sessions.

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