feat: add real-time recording visualization

[dotCipher]

Real-Time Recording Visualization

Adds live visual feedback during voice recording to improve UX and help users understand what's happening during recording sessions.

What This Does

Shows real-time recording feedback with:

• Audio level meter with color-coded RMS visualization (0-100%)
• Recording duration vs. maximum time
• Speech detection status (detected/not detected)
• State indicators: WAITING (yellow) → ACTIVE (green) → SILENCE (blue)
• Silence progress bar showing accumulation toward threshold
• Minimum duration progress before silence can stop recording

Example

╭─────────────────────────────── 🎤 Recording... ───────────────────────────────╮
│                                                                              │
│     Duration:  3.2s / 120.0s                                                 │
│        State:  ACTIVE                                                        │
│       Speech:  ✓ Detected                                                    │
│  Audio Level:  ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓░░░░░░░░░░░░  72%                │
│                                                                              │
╰──────────────────────────────────────────────────────────────────────────────╯

Why This Matters

Users previously had no visual feedback during recording, leading to:

• Uncertainty about whether the mic was working
• Confusion about when to speak (only feedback was an audio beep)
• Difficulty diagnosing audio issues
• No visibility into the VAD state machine

This PR solves these issues by making the recording process transparent and providing clear visual cues.

Implementation

New module (voice_mode/recording_visualization.py):

• RecordingVisualizer class with thread-safe updates
• Live display at 10 FPS using the Rich library
• Zero overhead when disabled

Integration (voice_mode/tools/converse.py):

• Real-time RMS calculation in audio callback
• State tracking (WAITING → ACTIVE → SILENCE)
• Proper cleanup on completion and errors

Configuration:

• Enabled by default for better UX
• Can be disabled via VOICEMODE_RECORDING_VISUALIZATION=false

Dependencies:

• Added rich>=13.0.0 for terminal UI

Testing

Manual test script included (test_visualization.py) that simulates:

1. Waiting for speech phase
2. Active recording with speech
3. Silence accumulation until threshold

Documentation

Comprehensive guide added at docs/features/recording-visualization.md:

• Feature overview and benefits
• Configuration options
• Technical details
• Troubleshooting common issues

Changes

• pyproject.toml - Added rich dependency
• voice_mode/config.py - Added RECORDING_VISUALIZATION_ENABLED setting
• voice_mode/recording_visualization.py - New visualization module
• voice_mode/tools/converse.py - Integrated visualizer into recording flow
• docs/features/recording-visualization.md - Feature documentation
• test_visualization.py - Manual test script

@mbailey this is a mostly complete draft, I want to do some more extensive testing on it, but mainly wanted to get my idea down for some feedback 👍🏻 cheers!