fix(ui5-dynamic-page): prevent unwanted header toggle from scroll

[NakataCode]

Issue:

1. The snapTitleByScroll function, triggered by scroll events, interfered with user-triggered actions such as onExpandClick and onToggleTitle. This caused the header to snap or close unexpectedly after being manually expanded.
2. In the "inbetweener" state (between SCROLL_THRESHOLD and headerHeight), the header wasn't properly unsnapping.

Solution:

1. An isToggled flag was introduced to temporarily prevent the snapTitleByScroll function from running right after a user-triggered toggle. This ensures that snapTitleByScroll doesn't fire immediately after a manual action. Once the user toggle is complete, the flag is reset, allowing normal scroll-based snapping to resume without conflict.
2. Added showHeaderInStickArea state synchronization when setting scrollTop to 0 in the inbetweener state, ensuring immediate and correct snap behavior on subsequent scrolls.

Fixes: #9961