$mcp_lib and $mcp_lib_version now on every event

0.6.0

Minor Changes

• #4022 d9e19e0 Thanks @gesh! - Emit $mcp_lib (@posthog/mcp) and $mcp_lib_version on every $mcp_* event (and the $exception sibling) so you can tell which analytics SDK release produced the data. The version was already resolved at runtime but never mapped to a property. Namespaced like @posthog/ai's $ai_lib rather than overriding $lib, which stays the transport SDK (posthog-node). (2026-06-30)