Enforce jsonschema formats and structural error path lookup (#56325)

* Initial plan

* Enforce jsonschema formats structurally

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

* Document nested schema causes

Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>

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Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: pelikhan <4175913+pelikhan@users.noreply.github.com>
Co-authored-by: Peli de Halleux <pelikhan@users.noreply.github.com>