SQLHelperFunctions — wrong Format masks in toISO

SQLHelperFunctions: correct toISO Format masks (mm vs nn)
- Component: `src/Modules/SQLHelperFunctions.bas` (top)

### Problem
- Uses month/minute masks incorrectly; minutes display as month.

### Snippet (actual)
```vb
Public Function toISO(dt) As String
toISO = Format(dt, "YYYY-MM-DD") & "T" & Format(dt, "HH:MM:SS")
End Function
```

### Expected
```vb
Public Function toISO(dt) As String
toISO = Format(dt, "yyyy-mm-dd") & "T" & Format(dt, "hh:nn:ss")
End Function
```

### Steps to Reproduce
1) Print `toISO(Now)` and compare minutes field.

### Actual
- Minutes are incorrect.

### Proposed Fix
- Use `mm` for month and `nn` for minutes.

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