chore: add changeset for Router popstate delta check improvements

Author: dennev

.changeset/stupid-camels-wash.md

@@ -0,0 +1,9 @@
+---
+"@solidjs/router": patch
+---
+
+Fix Router popstate event handling logic
+
+- Simplified delta check logic for history navigation
+- Improved reliability of forward navigation detection
+- Fixed window.history.forward() navigation handling