Factory function to create a new AgentRegistry.
Examples
if (FALSE) { # \dontrun{
# Create registry with agents
cleaner <- create_agent("Cleaner", "Cleans data")
plotter <- create_agent("Plotter", "Creates visualizations")
registry <- create_agent_registry(list(cleaner, plotter))
print(registry$list_agents()) # "Cleaner", "Plotter"
} # }