onStart/onFinish gesture callbacks, gesture type, new Sliders

[Azerlag]

Hi! For my project I needed to add new callbacks to the UI elements, so I forked the repo and made my own changes. Increase lib version please, I did not do that.

Compose components build successfully (only tested for AndroidRelease), artifacts are on jitpack: https://jitpack.io/#azerlag/colorpicker-compose

Thanks.

🎯 Goal

Add onStart/onFinish gesture callbacks to all interactive components,
introduce ColorChangeSource to ColorEnvelope, and add two new slider
components: HueSlider and SaturationSlider.

🛠 Implementation details

ColorChangeSource enum added to ColorEnvelope with three values:

• Tap — color changed via tap gesture
• Drag — color changed via drag gesture
• Programmatic — fallback for programmatic changes (e.g. initial setup)

The source is passed through the entire chain: gesture → controller →
notifyColorChanged → ColorEnvelope.

onStart / onFinish lambdas added to HsvColorPicker, AlphaSlider, BrightnessSlider and other. Implemented via detectTapGestures(onPress) and detectDragGestures(onDragStart, onDragEnd, onDragCancel).

HueSlider and SaturationSlider follow the same architecture as
AlphaSlider and BrightnessSlider. Controller gains hue, saturation
state fields, setHue/setSaturation methods, and isAttachedHueSlider/
isAttachedSaturationSlider flags. applyHSVFactors is updated accordingly.

✍️ Explain examples

HsvColorPicker(
    modifier = Modifier.size(200.dp),
    controller = controller,
    onColorChanged = { envelope ->
        when (envelope.source) {
            ColorChangeSource.Tap -> onTimeSendColor(envelope.color)
            ColorChangeSource.Drag -> sendingColor(envelope.color)
            ColorChangeSource.Programmatic -> Unit
        }
    },
    onStart = { /* user touched the picker */ },
    onFinish = { /* user lifted finger */ },
)

HueSlider(
    modifier = Modifier.fillMaxWidth().height(32.dp),
    controller = controller,
)

SaturationSlider(
    modifier = Modifier.fillMaxWidth().height(32.dp),
    controller = controller,
)