Fix iOS pinch-to-zoom initialization by listening to loadeddata event

[oNaiPs]

On iOS Safari, the <video> element often reports videoWidth/videoHeight as 0 when only loadedmetadata has fired. This causes DigitalPTZ.updateRects() to bail early, leaving this.videoRect unset and breaking pinch-to-zoom until a later navigation or redraw.

This PR adds an additional listener for the loadeddata event, which reliably fires once the first frame is available and dimensions are known. With this change, this.videoRect is correctly initialized on iOS and pinch-to-zoom works immediately.

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Changes

• Add videoEl.addEventListener("loadeddata", this.recomputeRects); in DigitalPTZ constructor
• Ensures this.videoRect is set when the video dimensions are first available on iOS

[AlexxIT]

Thanks!