Support exploding non-List collections (Set, Array) in `explode`

Problem

explode currently behaves differently depending on the collection type.

For List:

• top-level elements are unpacked into rows

For Set / arrays:

• behavior is inconsistent or not supported in the same way

Example expectation:

• List<List<T>> → explode unpacks only the top level
• Set<T> / Array<T> should behave the same way as List<T>

Currently this is not guaranteed or clearly defined.

Expected

explode should support common collection types consistently.

Defined behavior

• List, Set, and arrays are treated as collections
• explode unpacks only the top-level elements
• Nested collections are not recursively flattened

Acceptance criteria

• explode works for:
  • List<T>
  • Set<T>
  • Array<T>
• Behavior matches List semantics (top-level unpack only)
• Add tests for:
  • List<T>
  • Set<T>
  • Array<T>
• Document supported collection types

Motivation

Users expect explode to work for standard collection types.

Inconsistent behavior between List and other collections makes API harder to reason about.

This is a small but important consistency fix before 1.0.