Wrap numpy and voice_loop imports in try/except with pytestmark skipif.
Tests skip cleanly instead of ImportError when numpy not in dev deps.
Closes#48
Three fixes from real-world testing:
1. Event loop: replaced asyncio.run() with a persistent loop so
Agno's MCP sessions survive across conversation turns. No more
'Event loop is closed' errors on turn 2+.
2. Markdown stripping: voice preamble tells Timmy to respond in
natural spoken language, plus _strip_markdown() as a safety net
removes **bold**, *italic*, bullets, headers, code fences, etc.
TTS no longer reads 'asterisk asterisk'.
3. MCP noise: _suppress_mcp_noise() quiets mcp/agno/httpx loggers
during voice mode so the terminal shows clean transcript only.
32 tests (12 new for markdown stripping + persistent loop).
