Remove/accurately document SilentRenderer in architecture docs

[danieljsinclair]

Issue Type

Cleanup/Documentation Update

Severity

Medium - Outdated documentation references

Problem Statement

Documentation references SilentRenderer which was recently deleted from the codebase:

• src/audio/renderers/SilentRenderer.cpp - DELETED
• src/audio/renderers/SilentRenderer.h - DELETED

However, documentation may still reference it or show it in architecture diagrams.

Current State

• SilentRenderer files have been removed from codebase
• AudioPlayer.cpp has been updated to not use SilentRenderer
• Documentation needs to be audited and updated

Files to Check

• docs/AUDIO_MODULE_ARCHITECTURE.md - Check for SilentRenderer references in diagrams and text
• docs/ARCHITECTURE_TODO.md - Check for any mentions in cleanup sections
• Any other documentation files that might reference SilentRenderer

Acceptance Criteria

• All references to SilentRenderer removed from documentation
• Architecture diagrams updated to show current renderer options (SyncPullRenderer, ThreadedRenderer)
• Any historical notes about SilentRenderer moved to archive or removed if not relevant

Related Issues

• CRITICAL: Documentation describes non-existent NEW architecture (IAudioStrategy) #8 - CRITICAL: Documentation describes non-existent NEW architecture

Notes

This is a straightforward cleanup task to ensure documentation matches code after recent refactoring.