enhancement: GridDragScroll: Add delay and minDistance to prevent accidental drags

[tobiu]

Context

Currently, Neo.main.addon.GridDragScroll initiates a drag operation immediately upon a mousedown or touchstart event. This converts the cursor to grabbing instantly, which can feel aggressive and lead to accidental scroll starts when the user merely intended to click or select.

Objective

Adopt the delay and minDistance pattern found in Neo.main.draggable.sensor.Mouse to ensure drag operations are intentional.

Requirements

1. Add Configs:
   • delay: Default to 100 (ms).
   • minDistance: Default to 5 (px).
2. State Tracking:
   • Track mouseDownTime.
   • Track start coordinates.
   • Track mouseDownTimeout.
3. Logic Update:
   • onDragStart should not immediately set activeDrag or change the cursor.
   • Instead, it should start monitoring mousemove/touchmove.
   • The drag (and cursor change) should only activate once both conditions are met (following the Mouse.mjs pattern):
     • timeElapsed >= delay
     • distanceTravelled >= minDistance

Goal

Improve the "feel" of grid interactions by preventing accidental drags during normal click operations.

[tobiu]

Input from Gemini 3 Pro:

✦ Implemented delay (100ms) and minDistance (5px) checks in GridDragScroll.

• Added construct to bind handlers.
• Refactored onDragStart to initiate a monitoring phase.
• Added onMonitorMove to check both time and distance criteria before transitioning to active drag.
• This ensures drag operations are intentional and prevents accidental cursor changes on simple clicks.