Implement best practices for audio/video rate control

[nchapman]

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[Copilot]

Pull request overview

This PR implements dynamic rate control for audio/video synchronization based on Hans-Kristian Arntzen's "Dynamic Rate Control for Retro Game Emulators" (2012). The changes replace a deadband-based proportional controller with a mathematically proven continuous feedback algorithm that maintains audio buffer at 50% capacity, providing optimal headroom for timing jitter while keeping pitch adjustments inaudible.

Key changes:

• Replaced proportional controller with continuous formula: adjustment = 1 - (1 - 2*fill) * d
• Tightened resampler clamping from ±50%/±100% to ±1% to match the d=0.5% parameter
• Updated tests to work with smaller adjustment range (1% instead of 2%)
• Added comprehensive documentation explaining the algorithm and implementation

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
workspace/all/common/audio_resampler.h	Updated documentation to reflect ±1% clamping range
workspace/all/common/audio_resampler.c	Tightened clamping bounds from ±50%/±100% to ±1%, updated explanatory comments
workspace/all/common/api.c	Replaced deadband controller with Arntzen's continuous formula, inverted for resampler semantics
tests/unit/all/common/test_audio_resampler.c	Updated tests to use larger sample sizes and ±1% adjustments for reliable detection
docs/audio-rate-control.md	Added comprehensive documentation of algorithm, implementation, and rationale

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