defer output fetching for task/terminal to tools, add `GetTaskOutputTool`, add terminal last command context to prompt (#16)

* add task output tool and more

* update baseline

* Cap max chars

* add to agent tasks instructions

* follow run task example

* update baseline

* fix some issues

* revert a change

* update baseline

* undo update baseline

* rm files

* fix issue

* empty string instead of null

* Update baseline

* align with run task

* fix group

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Co-authored-by: Daniel Imms <2193314+Tyriar@users.noreply.github.com>