feat: add scanline

[damienmontastier]

This component introduces the <Scanline> effect, which simulates the scanlines of old CRT displays, adding a nostalgic or stylized visual aesthetic to your scene. The <Scanline> effect is part of the pmndrs/postprocessing package and can enhance your project with retro-inspired visuals or unique stylized effects.

• Enhances the retro aesthetic or stylized appeal of your scene with customizable scanline effects.
• Easy to set up — simply include it in your <EffectComposer> pipeline.
• Fully supports different blend functions for enhanced visual styles.
• The scrollSpeed property allows for animating the scanlines for a dynamic visual experience or keeping them static for a classic look.

For more details, see ScanlineEffect on pmndrs/postprocessing.

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