Undisposed resource problem in the generated codes

This is part of the generated code
```csharp
CompositionEffectFactory EffectFactory()
{
var compositeEffect = new CompositeEffect();
compositeEffect.Mode = CanvasComposite.DestinationIn;
compositeEffect.Sources.Add(new CompositionEffectSourceParameter("destination"));
compositeEffect.Sources.Add(new CompositionEffectSourceParameter("source"));
var result = _c.CreateEffectFactory(compositeEffect);
return result;
}
```
It is not using the `using` keyword for the `CompositeEffect` object being created, leaving undisposed resources. GitHub CodeQL scans also confirm this problem:

The correct code would be this:
```csharp
CompositionEffectFactory EffectFactory()
{
using CompositeEffect compositeEffect = new();
compositeEffect.Mode = CanvasComposite.DestinationIn;
compositeEffect.Sources.Add(new CompositionEffectSourceParameter("destination"));
compositeEffect.Sources.Add(new CompositionEffectSourceParameter("source"));
var result = _c.CreateEffectFactory(compositeEffect);
return result;
}
```

## Explanation

After `CreateEffectFactory` has created the `CompositionEffectFactory`, the code does not need the original `CompositeEffect` instance anymore. Disposing the local `CompositeEffect` after factory creation does not dispose the `CompositionEffectFactory` or the `CompositionEffectBrush` created from it. `EffectBrush()` creates the factory, creates a brush from it, sets the two source parameters, and returns the brush, so the `CompositeEffect` lifetime can end inside `EffectFactory()`.

## Details

* .NET 10
* Visual Studio latest version
* LottieGen version: 8.2.250604.1
* Command: `LottieGen -Language CSharp -Public -WinUIVersion 3.0 -InputFile Item.json`

Start with the LottieGen entry point using the supplied `LottieGen -Language CSharp -Public -WinUIVersion 3.0 -InputFile Item.json` command, then locate where the generated `EffectFactory()` code is emitted. Regenerate the C# output and verify that the `CompositeEffect` is disposed after factory creation without changing the returned factory or brush behavior; the CodeQL resource warning should be resolved.

Written by the indexing model from the issue text.