`ORDER BY` may fail on Apache AGE when it references a property of a node value returned under an alias.

**Describe the bug**
`ORDER BY` may fail on Apache AGE when it references a property of a node value returned under an alias.

In the minimized repro below, the query returns `n AS person` and then sorts by `person.name`. Neo4j and Memgraph both accept this and return the expected rows.

Instead, AGE fails with:

```text
could not find rte for person
```

and reports that `person` is out of scope.

**How are you accessing AGE (Command line, driver, etc.)?**
- PostgreSQL `cypher(...)` wrapper through the local Python differential-testing harness
- Reproducible directly in `psql` inside the Docker container

**What data setup do we need to do?**
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
CREATE (:Person {name: 'Alice'}),
(:Person {name: 'Bob'}),
(:Person {name: 'Charlie'})
$$) AS (v agtype);
```

**What is the necessary configuration info needed?**
- Plain Apache AGE Docker image was enough
- Docker image in local repro: `apache/age`
- AGE extension version: `1.7.0`
- PostgreSQL version: `18.1`
- Graph name used in repro: `fuzz_graph`
- No extra extensions or special configuration were required

**What is the command that caused the error?**
```pgsql
SELECT * FROM cypher('fuzz_graph', $$
MATCH (n:Person)
RETURN n AS person
ORDER BY person.name DESC
LIMIT 2
$$) AS (person agtype);
```

Returned result on AGE:
```text
ERROR: could not find rte for person
HINT: variable person does not exist within scope of usage
```

**Expected behavior**
The query should succeed and return the two lexicographically largest `Person` nodes by `name`.

Observed behavior on Neo4j and Memgraph:
```text
Charlie
Bob
```

**Environment (please complete the following information):**
- Version: Apache AGE `1.7.0`
- PostgreSQL: `18.1`
- Host OS: Windows
- Architecture: x86_64
- Deployment: Docker

**Additional context**
Two nearby control cases behave correctly on the same AGE instance:

1. Sorting by the original variable instead of the return alias:

```pgsql
SELECT * FROM cypher('fuzz_graph', $$
MATCH (n:Person)
RETURN n AS person
ORDER BY n.name DESC
LIMIT 2
$$) AS (person agtype);
```

AGE returns the expected two rows there.

2. Sorting by a scalar alias also works:

```pgsql
SELECT * FROM cypher('fuzz_graph', $$
MATCH (n:Person)
RETURN n.name AS person
ORDER BY person DESC
LIMIT 2
$$) AS (person agtype);
```

AGE also returns:
```text
Charlie
Bob
```

So the issue appears specific to property access through a return alias that holds a node value, rather than to `ORDER BY` aliases in general.