fix: eliminate scroll log spam and restore XTest controlKey atomicity

- Remove warn-level log on every scroll when xinput driver is unavailable
  (dummy driver returns error by design, not worth logging)
- Pass controlKey to xorg.Scroll() in the XTest fallback path so the
  modifier set/scroll/clear happens atomically under a single X11 lock

Made-with: Cursor

Author: hiroTamada

server/internal/desktop/xorg.go

@@ -19,15 +19,17 @@ func (manager *DesktopManagerCtx) GetCursorPosition() (int, int) {
 }
 
 func (manager *DesktopManagerCtx) Scroll(deltaX, deltaY int, controlKey bool) {
-	if controlKey {
-		xorg.SetKeyboardModifier(xorg.KbdModControl, true)
-		defer xorg.SetKeyboardModifier(xorg.KbdModControl, false)
+	// Try xinput driver first (XI2.1 smooth scrolling via xf86-input-neko)
+	if err := manager.input.Scroll(int32(deltaX), int32(deltaY)); err == nil {
+		if controlKey {
+			xorg.SetKeyboardModifier(xorg.KbdModControl, true)
+			defer xorg.SetKeyboardModifier(xorg.KbdModControl, false)
+		}
+		return
 	}
 
-	if err := manager.input.Scroll(int32(deltaX), int32(deltaY)); err != nil {
-		manager.logger.Warn().Err(err).Msg("xinput scroll failed, falling back to XTest")
-		xorg.Scroll(deltaX, deltaY, false)
-	}
+	// XTest fallback — handles controlKey atomically under a single X11 lock
+	xorg.Scroll(deltaX, deltaY, controlKey)
 }
 
 func (manager *DesktopManagerCtx) ButtonDown(code uint32) error {