Claude Code 2.1.212 adds /fork, subagent caps, WebSearch limit

Version 2.1.212 introduces `/fork` to copy conversations into a new background session, and sessions now have a default limit of 200 WebSearch tool calls and 200 subagent spawns. MCP tool calls running longer than 2 minutes automatically move to background, and `/resume` opens a picker for past sessions including deleted ones. Several bug fixes address plan mode permissions and SIGTERM handling.