docs: clarify pinch guard fallbacks

Co-authored-by: siarheihuzarevich <13272876+siarheihuzarevich@users.noreply.github.com>

Author: Copilot

projects/f-flow/src/f-zoom/f-zoom.directive.ts

@@ -232,6 +232,7 @@ export class FZoomDirective extends FZoomBase implements OnInit, AfterViewInit,
 
   private _getTouchDistance(touches: TouchList): number {
     if (touches.length !== 2) {
+      // Callers guard for pinch-ready touch events; return neutral distance if the check is bypassed.
       return 0;
     }
 
@@ -246,6 +247,7 @@ export class FZoomDirective extends FZoomBase implements OnInit, AfterViewInit,
 
   private _getTouchCenter(touches: TouchList): IPoint {
     if (touches.length !== 2) {
+      // Callers guard for pinch-ready touch events; return neutral center if the check is bypassed.
       return PointExtensions.initialize();
     }