SQLSubselect — Property Get returns wrong variable

SQLSubselect: SelectAs getter returns wrong variable
- Component: `src/ClassModules/SQLSubselect.cls` (around 0–39)

### Problem
- Getter returns an undefined identifier instead of the backing field.

### Snippet (actual)
```vb
Property Get SelectAs() As String
SelectAs = aAs
End Property
```

### Expected
```vb
Property Get SelectAs() As String
SelectAs = sAs
End Property
```

### Steps to Reproduce
1) Read `SelectAs` from an instance.

### Actual
- Returns empty/undefined; potential compile/runtime error.

### Proposed Fix
- Return `sAs`.

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