Add workflow parameter access in config blocks

[LasmarKhalifa]

Closes #1006

Workflow params (target!, targets, arg?, args, kwarg, kwarg!, kwarg?, kwargs) are currently only available in execute blocks. This PR makes it possible to read them inside cog config blocks and the global block, so cogs can be configured based on how the workflow was invoked.

Example usage:

config do
  chat do
    model(arg?(:fast) ? "gpt-5.4-nano" : "gpt-5")
  end
  global do
    abort_on_failure! if arg?(:strict)
  end
end

They are not available in the top-level config do body, only within the cog / global blocks nested inside it.

The accessors mirror the execute-side ones on CogInputContext with identical behavior.

[LasmarKhalifa]

• Add workflow parameter access in config blocks #1030 👈 (View in Graphite)
• main

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