Add chorus effect with UI controls

[bhurlow]

Add optional chorus effect to the final stage output with toggle and effect amount controls in the debug-ui.

Implementation includes:

• Chorus effect algorithm with delay line and LFO modulation
• Integration into Stage audio processing pipeline
• WASM bindings for web interface
• UI controls (toggle + mix amount slider) in debug-ui

Resolves ##57

Generated with Claude Code

[bhurlow]

@claude I would like the chorus implementation to be in an effects directory as I plan to add others

[bhurlow]

Claude finished @bhurlow's task —— View job

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Todo List:

• Read current chorus implementation and understand the structure
• Create new effects directory and module structure
• Move chorus implementation from filters to effects
• Update all import statements and references
• Remove old chorus.rs file from filters directory
• Test that changes work properly

✅ Complete

Successfully reorganized the chorus effect into an effects directory as requested. The changes include:

• Created new effects directory with proper module structure
• Moved chorus.rs from lib/src/filters/ to lib/src/effects/
• Updated imports in stage.rs and lib.rs to use the new location
• Removed chorus references from the filters module
• Maintained all existing functionality - all WASM bindings and UI controls remain unchanged

The chorus effect is now properly organized in the effects directory, making it easier to add additional effects in the future as planned. All existing functionality has been preserved and the API remains the same.

[bhurlow]

@claude this doesn't sound particularly chorusy or good. Add an intensity slider along with the % mix, and increase the modulation amount

[bhurlow]

Claude finished @bhurlow's task —— View job

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✅ Complete

Successfully enhanced the chorus effect with an intensity parameter and improved modulation characteristics. The chorus should now sound much more chorusy and dynamic!

Todo List:

• Read current chorus implementation to understand algorithm
• Read UI code to see current control structure
• Enhance chorus algorithm with intensity parameter and improved modulation
• Add intensity slider to debug UI
• Update WASM bindings for new parameter
• Update stage integration for intensity parameter
• Test changes and commit improvements

Improvements Made:

🎛️ New Intensity Parameter:

• Added intensity control (0.0-1.0) that scales both modulation depth and LFO frequency
• Default intensity is 0.7 (70%) for a good balance
• Intensity slider added to UI alongside existing mix control

🎵 Enhanced Chorus Algorithm:

• Increased modulation depth from ±5ms to ±10ms (2x stronger)
• Improved LFO frequency from 0.5 Hz to 1.2 Hz (more classic chorus speed)
• Dynamic scaling - intensity affects both depth and frequency for more realistic effect
• Better chorusing - should sound much more pronounced and musical

🔧 Technical Implementation:

• Added intensity parameter to Chorus struct
• Updated Stage integration with intensity methods
• Added WASM bindings for web interface
• Added intensity slider to debug UI following existing patterns

The chorus effect should now sound much more chorusy and provide better control over the effect intensity. The combination of increased modulation depth, faster LFO, and the new intensity parameter should address the original feedback about the effect being too subtle.

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