Menu: touch swipe-to-scroll with tap disambiguation, fling, wider scrollbar

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

AGENTS.md

@@ -174,7 +174,7 @@ device only; the editor has an XR simulator for dev. Trackers/action map: see `x
   0.6 cm presses, backing out past 1.8 cm releases (hysteresis; entering from the side/behind
   never presses) — buttons fire on release like a real tap, sliders drag while touching.
   Farther away = LASER cursor, trigger clicks/drags (edge-triggered: a trigger already held
-  never clicks). Thumbstick Y while hovering = mouse wheel (scroll containers). One Godot mouse
+  never clicks). Thumbstick Y while hovering = mouse wheel (scroll containers); touch on a scrollable area = swipe-vs-tap (press held back, > 6 mm travel scrolls + flings, else a tap is sent at the contact point). One Godot mouse
   per viewport → one owning hand (press holder ≻ touching hand ≻ laser). Cursor dot per hand
   (shrinks as the tip nears = proximity cue), haptic tick on press, synthesized click
   (code-generated `AudioStreamWav`, no asset). Menu actions run DEFERRED (never from inside