Less repeated work when agent runs start and finish

The runner now avoids several repeated steps when starting an agent session. It reuses local tool binaries and Pi skill copies where applicable, mounts drives in parallel, and reuses a harness capability probe.
When its trace is ready, a completed Pi turn no longer waits for the full trace-drain polling window. Organization owners and admins can test their connections from a project that does not use them. Conversation replay no longer cuts through a character and leaves a chat unable to continue.