MCP analytics instrumentation ships

Minor changes

• 888a725 Add posthog.mcp, a Python SDK for PostHog MCP analytics (just pip install posthog; the MCP SDK is a peer dependency of instrument(), not bundled). instrument(server, posthog_client) wraps a FastMCP or low-level mcp.server.Server so every tool call, agent intent, tools/list, initialize, and failure is captured to PostHog as a $mcp_* event. Also adds PostHogMCP, a Client subclass for custom dispatchers (needs nothing beyond posthog), plus opt-in context intent capture, identify, report_missing (get_more_tools), and conversation_id. Beta. — Thanks @lucasheriques for your first contribution 🎉!