Hands a decision from before_tool to wrap_tool for the same tool call.

before_tool runs in the conversation machine, wrap_tool in the tool task, and the machine must not block on a human (it would stop answering cancel, steer, get_state and compact). So a plugin that wants an answer from a human lets the call through in before_tool, leaves a note here and asks in wrap_tool, which runs in the task. The note is keyed by conversation and tool call id. take/2 removes it. A note that nobody takes (a later plugin blocked the call) expires after ten minutes and is dropped on the next put/3.