Enrich List operations

[imperugo]

Summary

Expand List API beyond the current minimal coverage (only AddToLeft and GetFromRight).

Missing Methods

• `ListLengthAsync` — get list size
• `ListRangeAsync` — get range of elements
• `ListIndexAsync` — get element at index
• `ListSetByIndexAsync` — set element at index
• `ListTrimAsync` — trim list to range
• `ListRemoveAsync` — remove elements by value
• `ListInsertBeforeAsync` / `ListInsertAfterAsync` — insert at position
• `ListRightPushAsync` — push to right (complement to existing AddToLeft)
• `ListLeftPopAsync` / `ListRightPopAsync` — pop operations
• `ListMoveAsync` — atomic move between lists