5fdcfd851f
Salvages #22981 by @SimbaKingjoe. Adds 'kanban.max_in_progress' config that caps simultaneously running tasks. When the board already has N running, dispatcher skips spawning so slow workers (local LLMs, resource-constrained hosts) don't pile up and time out. Threads through dispatch_once(max_in_progress=) and gateway dispatcher config parsing with validation (warns on invalid/below-1 values).