docs: document workflow loop guardrails

[rosomri]

Summary

• Document loop-level guardrails for foreach and while workflow steps: max-iterations, timeout, on-failure, and if.
• Document iteration-level guardrails: iteration-timeout and iteration-on-failure.
• Update the flow-control overview and error-handling restrictions so they align with the new loop guardrail behavior.

Testing

• Checked diagnostics for the edited docs files with ReadLints.
• Reviewed the final git diff before committing.

[github-actions]

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🔍 Preview links for changed docs

• explore-analyze/workflows/authoring-techniques/pass-data-handle-errors.md
• explore-analyze/workflows/steps/flow-control-steps.md
• explore-analyze/workflows/steps/foreach.md
• explore-analyze/workflows/steps/while.md

[github-actions]

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[charlotte-hoblik]

Thank you, 🙂 clean change, and the applies_to tagging is spot on. I left a few inline suggestions.

One thing that's better as a manual move than a suggestion:

Could we move the ## Guardrails section to sit between ## Context variables and ## Example? Where it is now, its ga 9.4+ badge also covers the pre-9.4 "expression types" intro that follows it.