SELECT with boolean logic fails with syntax error

It's possible in SQL to check values for equality in a SELECT, which fails when using SQLair.

```
SELECT (num = 1) AS (&isOne.*)
FROM nums
```

Fails with:

```
near "(": syntax error
```

Which also isn't very helpful. There are more than one `(` in this query. Positional information would have been useful.

Start by reproducing the SQLair query `SELECT (num = 1) AS (&isOne.*) FROM nums` and inspect the query-processing entry point and error path that reports the syntax error. Done means boolean expressions in SELECT statements work as shown and syntax errors identify the relevant position rather than an ambiguous opening parenthesis.

Written by the indexing model from the issue text.