Touch controls: validate + tune gesture constants for tablet gameplay

[fadi-labib]

Summary

The iOS touch→mouse gesture translator is enabled on Android (GX_TOUCH_UI) and works, but its constants were tuned for iPhone/iPad. Validate and tune them for the Tab S7+ (2800×1752) in real gameplay.

What to check (in a real skirmish, on-device)

• LONG_PRESS_MS = 600, TAP_DEAD_ZONE_PX = 8, PINCH_STEP_RATIO = 0.06 in GeneralsMD/Code/GameEngineDevice/Source/SDL3GameEngine.cpp.
• The 8 px dead zone may be too small at 2800×1752 (a tap can register as a drag-box).
• Long-press → right-click timing, two-finger pan, pinch-zoom feel during actual play (build a base, box-select units, issue move/attack orders).

Notes

• adb input tap has a 0 ms down-up and does NOT activate menus (the deferred click lands in the hover frame) — use adb shell input swipe X Y X Y 150 to emulate a real finger, or test by hand.
• Needs a human playing to judge feel; the mechanics themselves are verified working.

Impact

Playability polish. Core touch works; this is comfort/accuracy tuning. Branch: feature/android-phase3-renderer.