fix(array): recursively validate nested arrays

[fallintoplace]

What

Make top-level Validate and ValidateFull walk nested array data. Parent layouts, child counts and types, dictionary indices and values, and extension storage are checked before recursive validation. Errors include a path such as field "orders" -> list values -> field "name". Ordinary list and large-list offsets are now validated fully as well.

Tests

• go test ./arrow/array -count=1
• GOOS=linux GOARCH=386 go test -c -o /dev/null ./arrow/array
• pre-commit run golangci-lint-full --all-files

Regression coverage includes malformed Struct -> List -> Struct -> String, dictionary values, and non-monotonic list offsets.