Add TouchPlugin to handle text selection by touch

[vinguyen12]

Add Touch Plugin, Pointer Event type (pointer up, pointer down).

Use DomEventPlugin to recognize pointer event and trigger newly created pointer plugin event. Touch Plugin event will be used to handle cursor selection for text.

(Spec: For touch selection, move the cursor to the beginning or end of the word if they tap within 6 characters of the beginning/end. If not, then place the cursor where they originally tapped.)

[Copilot]

Pull Request Overview

This PR implements touch selection repositioning behavior to improve text cursor placement on touch devices. When users tap within 6 characters of a word's beginning or end, the cursor moves to the nearest word boundary; otherwise, it remains at the original tap position.

Key changes:

• Add new repositionTouchSelection function with word boundary detection logic
• Integrate touch selection handling into the SelectionPlugin with timeout delay
• Export the adjustWordSelection utility function for reuse

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 4 comments.

File	Description
repositionTouchSelection.ts	New module implementing touch selection repositioning logic with 6-character threshold
SelectionPlugin.ts	Integration of touch selection handler with 200ms timeout and import addition
index.ts	Export of adjustWordSelection utility function

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