Add voice output (text-to-speech) to HumanCLI for Go2

[spomichter]

Issue

Add voice output capability to HumanCLI so the agent can speak responses instead of just displaying text. Validate that it works on the Unitree Go2 platform.

Requirements

• Implement text-to-speech using Python audio libraries (e.g., pyttsx3, gTTS, espeak, or similar)
• Add directly to HumanCLI module (dimos/agents/cli/human.py)
• Support audio output on Go2 (speakers/audio device)
• Handle audio device selection/configuration
• Test on actual Go2 hardware

Implementation Considerations

• Use lightweight TTS that runs on-device or can call external API
• Low latency for real-time responses
• Voice should be clear and understandable in robot environment
• Toggle for enabling/disabling voice output
• Option to stream long responses instead of waiting for full synthesis

Acceptance Criteria

• Voice output works on Go2
• Agent responses are spoken aloud
• Audio quality is acceptable for human understanding
• User can toggle voice on/off
• Works alongside text output (not exclusive)

Related

• Pair with: Voice input (STT) issue (Add voice input (speech-to-text) to HumanCLI for Go2 #1272)