Changes:
- Add CallManager singleton to ensure only 1 call per device at a time
- Hide Debug tab from production (href: null)
- Remove speaker/earpiece toggle button (always use speaker)
- Agent uses voice_ask API (fast ~1 sec latency)
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
