Support max_iterations config in agent yaml

[krissetto]

Allows users to set a max_iterations value in their agent config, and creates a max_iterations_reached event that can be consumed by clients.

If max_iterations is not explicitly set, it is considered to be unlimited

Example config:

version: 2

agents:
  root:
    model: dmr/ai/smollm3:latest
    description: Bob
    instruction: You are a helpful AI assistant named "Bob"
    max_iterations: 5
    toolsets:
      - type: shell

Screenshot

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closes #227

[rumpl]

Neat