fix(range): emit correct value when knob is at start of bar (#29820)

Issue number: resolves #29792

---------

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## What is the current behavior?
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When the user drags the range knob (most easily reproduced in fullscreen
mode) and the gesture emits a current x position of `0`, the range
incorrectly emits a value of `NaN`.

## What is the new behavior?
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this PR. -->

- `ion-range` does not emit `NaN` and instead emits the correct range
value for the knob

## Does this introduce a breaking change?

- [ ] Yes
- [ ] No

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## Other information

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screenshots of how the component looks before and after the change. -->

core/src/components/range/range.tsx

@@ -449,7 +449,7 @@ export class Range implements ComponentInterface {
    */
   private onEnd(detail: GestureDetail | MouseEvent) {
     const { contentEl, initialContentScrollY } = this;
-    const currentX = (detail as GestureDetail).currentX || (detail as MouseEvent).clientX;
+    const currentX = (detail as GestureDetail).currentX ?? (detail as MouseEvent).clientX;
 
     /**
      * The `pressedKnob` can be undefined if the user never