Feature: Touch drag (marquee) selection in tablet mode

### What feature or improvement do you think would benefit Files?

Summary
Add support for finger-based drag (marquee / box) selection when using Files on touch devices (tablet mode / 2-in-1 laptops).

Currently, drag selection works with mouse / trackpad input, but not with finger touch. Finger drags are interpreted as scroll gestures, making multi-select difficult in tablet mode.

Use case
I use Files on a 2-in-1 Windows laptop in tablet mode. When selecting multiple files, the current workflow requires tapping individual checkboxes or items. Due to small hit targets, this often results in missed taps or accidental deselection.

Windows File Explorer already supports finger drag selection (press, hold briefly, then drag to create a selection box). Files lacks this parity, which makes it less usable in tablet mode.

Expected behavior
- Touching empty space and **pressing-and-holding briefly**, then dragging with a finger, creates a selection rectangle (same behavior as Windows File Explorer).
- Files within the rectangle are selected
- Scrolling behavior remains unchanged when dragging outside empty space
- Behavior matches File Explorer’s touch marquee selection

Current behavior
- Finger drag always scrolls the view
- Marquee selection only works with pointer-class input (mouse / trackpad / pen-as-mouse)
- Touch users must rely on checkboxes or individual taps

### Requirements

Proposed requirements
1. Detect finger touch drag starting from empty space as a selection gesture
2. Add a short press-and-hold threshold to differentiate scroll vs selection
3. Enable marquee selection for touch input, not just pointer input
4. Maintain existing scroll behavior when dragging on items
5. Match File Explorer’s touch selection behavior for consistency

### Files Version

4.0.21.0

### Windows Version

Windows 11 Version 24H2 (OS Build 26220.7051, Beta channel with ViVeTool enabled features)

### Comments

This feature was discussed in the Files Community Discord on December 12, 2025 but thought it was better to put here for better tracking (#ideas → selecting in tablet mode).