️🛠 - Add basic reverb implementation

[maxwellmattryan]

Description

Implement an algorithmic reverb using the classic Freeverb architecture (Schroeder/Moorer style). This consists of:

• Parallel comb filters (typically 8) for initial echo density
• Series allpass filters (typically 4) for diffusion
• Wet/dry mix control
• Room size / decay time control
• Damping (high-frequency absorption)

Freeverb is well-documented, CPU-efficient, and produces a recognizable "digital reverb" character suitable for many applications.

Open questions

• Should stereo width be controllable?
• Pre-delay parameter? (Time before reverb onset)
• Should the reverb support modulation for a more "lush" sound?
• What's an acceptable CPU budget relative to other blocks?

Acceptance criteria

• Dry signal is unaffected when mix is set to 0%
• Reverb tail decays naturally without metallic ringing or obvious periodicity
• Room size parameter affects perceived space (small room to large hall)
• Damping reduces high-frequency content in the reverb tail
• Reverb does not add significant DC offset or noise floor
• CPU usage is reasonable for real-time use (benchmark against other blocks)

Tasks

TBD