AGE entity-projection alias audit

[YGY-001]

Environment: Apache AGE 1.8.0, PostgreSQL 18.1, image

Reproduction

CREATE (n {id: 1})
WITH n AS alias0
MATCH (alias0)
RETURN alias0

Observed error:

ERROR: variable 'alias0' already exists

The same error occurs after a second boundary:

CREATE (n {id: 1})
WITH n AS alias0
WITH alias0
MATCH (alias0)
RETURN alias0

The two renamed-alias queries both produced the existing-variable error. The
control query below succeeded and returned the created vertex:

CREATE (n {id: 4})
WITH n
MATCH (n)
RETURN n

Therefore this is not a generic prohibition on reusing an already-bound
pattern variable. The failure is specific to the entity projection alias.