feat: sequence supervisor

[pkarw]

Related #68
For some complex tasks where the supervisor naturally lacks domain knowledge, it would be easier to describe the workflow using a detailed task-by-task flow (with some space for conditional logic, etc.)., writing the flow in plain English but not leaving so much space as we do right now.

For this purpose, there could be a special purpose supervisor doing exactly this - getting step-by-step without splitting the tasks furthermore

[pkarw]

Let's imagine the current dispatcher - let's call it planningDispatcher for a while - and the new one sequenceDispatcher is producing a execution plan - tasks, agents etc - in a format that sequenceDispatcher is consuming.

Having this we'd have two scenarios - first user could define exact execution flow/plan and user sequenceDispatcher or can leave it to planningDispatcher

By having these 2 steps separated we'll end up with more deterministic flows - where execution always goes the same path (up to differences caused by agents themselves which are still dynamic) - and we could implement it as a kind of caching strategy for execution planning