[orchestra:var:NAME] should resolve nested variable paths (e.g. validation.comment), like flow conditions

Workflow flow conditions already resolve nested variable paths, e.g. validation.result where validation is a {result, comment} array. The [orchestra:var:NAME] token does not: [orchestra:var:validation.comment] looks for a literal top-level key validation.comment, finds none, and clears; [orchestra:var:validation] dumps the whole array as JSON.

Make the token consistent with flow conditions: when the flat key is absent, resolve the name as a dot-path into the (branch-visible) variables (NestedArray::getValue() over explode('.', $name)). So [orchestra:var:validation.comment] returns just the comment.

Benefits any template or message that references a nested result variable (for example an Easy Email or Orchestra Mail body printing a validator's rejection comment). Scalar leaves render as before; a non-scalar leaf still falls back to JSON.