fix(header): allow sorting on mobile devices with reorderable enabled

[spike-rabbit]

Description

On mobile devices, sorting was not working when tapping on a header due to a conflict with the [reorderable] input. The touchstart handler in the draggable directive was calling event.preventDefault() immediately, which prevented the synthetic click event from firing.

Changes

• Removed preventDefault() from touchstart handler in DatatableDraggableDirective
• Added setDragging() method to properly manage column.dragging state
• Added guard if (this.touchId !== undefined) to ensure drag only starts if touch is still active after delay
• Added test verifying short touch taps don't trigger drag start

How It Works

• Short tap (before the 500ms drag delay): No drag starts, click event fires normally → sorting works
• Long press (after the delay): Drag starts, column.dragging is set to true, sort handler skips

Testing

All 191 unit tests pass.

Closes #692

[gemini-code-assist]

Code Review

This pull request updates the DatatableDraggableDirective to manage dragging state via a new setDragging helper, removes event.preventDefault() on touch start to allow click events to proceed, and adds a corresponding unit test. The review feedback suggests improving the touch-start race condition check by verifying the specific touch identifier instead of just checking if it is defined, and wrapping the unit test's fake timer logic in a try...finally block to prevent test flakiness in case of assertion failures.

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[Copilot]

Pull request overview

Fixes mobile header sorting when column reordering is enabled by avoiding suppression of the synthetic click generated from touch interactions, while still supporting long-press drag behavior for reordering.

Changes:

• Removed preventDefault() from touchstart and moved touch cancellation to touchmove once dragging begins.
• Added setDragging() to manage column.dragging during drag lifecycle so sort can be skipped only when an actual drag starts.
• Added a unit test for short touch interactions before the drag delay.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 4 comments.

File	Description
projects/ngx-datatable/src/lib/directives/draggable.directive.spec.ts	Adds/adjusts unit tests around delayed touch interactions to ensure short touches don’t start a drag.
projects/ngx-datatable/src/lib/directives/datatable-draggable.directive.ts	Updates touch handling to allow click-based sorting on mobile while preserving delayed drag start and drag state.

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[fh1ch]

LGTM 👍