Module qualify_columns 

Qualify columns optimizer pass.

Resolves column references by:

• Expanding SELECT * to explicit column lists from schema
• Expanding SELECT t.* to columns from table t
• Adding table qualifiers to unqualified columns (e.g., col → t.col)
• Validating column existence against the schema
• Resolving columns through CTEs and derived tables

Functions

qualify_columns

Qualify columns in a statement using the provided schema.