fix(reactions): Prevent accidental reaction toggle when long pressing

[luflow]

Summary

• Fixes accidental reaction toggles when users long press on a reaction to view "who reacted"
• Tracks touch duration to differentiate quick taps from long press attempts
• Only triggers reaction toggle for taps ≤ 0.25 seconds

Problem

When long pressing on a reaction bubble to see "who reacted", users would sometimes accidentally toggle the reaction (add/remove it) if they released their finger before the context menu threshold (~0.5s) was reached.

Root Cause

The ReactionsView (UICollectionView) handles taps via didSelectItemAt independently of the table view's context menu system. When a long press didn't quite reach the context menu threshold, the touch was interpreted as a tap, triggering an unwanted reaction toggle.

Solution

Track the touch duration in ReactionsView:

• touchesBegan records the start time
• touchesCancelled clears it
• didSelectItemAt checks the duration:
  • ≤ 0.25s → Quick tap → Toggle reaction ✓
  • > 0.25s → Long press attempt → Ignore (context menu handles it)

This threshold (0.25s) provides a buffer below the context menu's ~0.5s threshold while still allowing normal quick taps to work.

Test plan

• Quick tap on a reaction toggles it (adds/removes your reaction)
• Long press on a reaction shows "who reacted" summary
• Releasing a long press early (before context menu appears) does NOT accidentally toggle the reaction
• Scrolling away from a reaction does not trigger any action