pickAttentionAgent now skips agents with a parentAgentId. The
workspace auto-focus path was opening subagents as tabs when they
needed attention, breaking the rule that subagents only become tabs
when the user explicitly clicks them.
When navigating to a workspace, auto-open the tab for the agent that
most urgently needs attention (permission > error > finished, oldest
first). Adds pickAttentionAgent + wires it into navigateToWorkspace.
Mohamed Boudra