AgentSelector used useAgentsStore which is only warm after a chat session
loads, so the todo send dialog opened from the project context panel showed
an empty agent list. Prefer useConfigStore.agents (the same source ModelControls
uses in chat) with useAgentsStore as fallback, and load both on mount when
neither is populated.
Also set the primary-mode filter on the scheduled task editor agent selector
to keep its options consistent with the other flows.