Method GeneratePvtSelect(IReadOnlyList<FieldInfo>, string)

Generates PVT subquery for SELECT (data retrieval) - T-SQL syntax.
Uses MAX(CASE WHEN) for scalar fields - single pass optimization.
Supports ListItem.Value/Alias via JOIN with _list_items.

public string GeneratePvtSelect(IReadOnlyList<FieldInfo> fields, string tableAlias = "o")