Applying job code changes

In #490, we addressed job code edit scenarios involving a single job code step. In this issue, we'll focus on more complex scenarios involving more than one step, or more than one agent.

Test scenarios

• User asks for a change to the current step that requires information from other steps ("make this step like my last step", "do the same elsewhere", "check for x in all steps")
• User asks for a change to a different step from another step/workflow view
• User asks for several changes across steps from one step/workflow view
• User asks to "add a step in my workflow to...[do something vague]" -> ok to call workflow agent directly and leave the code empty
• User asks to "add a step in my workflow to...[do something specific]" -> to fill in the code, we need to call the planner, workflow subagent and the job code subagent.

Apollo architecture work:

• Make sure the planner is able to and encouraged to examine any relevant parts of the full YAML with the YAML tool
• Verify that the internal YAML is kept up to date between tool calls, especially concurrent tool calls.
• Adjust payload to return the full YAML only, not YAML + a single changed step (see below)

Required changes in Lightning:

• Essential for this to function: Currently, we can't implement changes in several steps from the job code view, as Lightning expects to receive a single job code change. We should update Lightning to consume YAML-only updates so the job-code agent can return multi-step changes in full and without mixing up steps.
• Essential for UX, but not for an experimental feature: A way to signal to the user from any workflow view/job code view which steps were changed.