Feature Request: Datagrid Frozen Rows

[peachnektari]

Is your feature request related to a problem? Please describe.
Yes. In the current RadzenGrid, there is no built-in way to “freeze” or pin specific rows so that they remain visible while the rest of the data scrolls. When working with large datasets or needing to keep summary or key rows in view, I lose track of those rows as soon as I scroll.

Describe the solution you'd like
Introduce a FrozenRows feature on RadzenGrid where:

• You can mark one or more rows as frozen/pinned.
• A new FrozenRowsPosition property lets you choose whether those rows appear fixed at the top or bottom of the grid.

For example:

<RadzenGrid Data="@items"
            FrozenRows="@pinnedItems"
            FrozenRowsPosition="Top">
    …
</RadzenGrid>

Describe alternatives you've considered

• Custom CSS or JavaScript hacks to reposition rows on scroll—but these are brittle, break grouping/filtering, and aren’t officially supported.
• Manually duplicating a “header” or “summary” row above or below the grid—this requires duplicating data and doesn’t stay in sync when the grid is updated or re-sorted.

Additional context
A native frozen-row capability would pair nicely with the existing frozen-column feature, allowing scenarios like:

• Keeping a grand total or summary always visible at the bottom.
• Pinning an “active” record at the top while browsing other entries.
• Highlighting special rows (e.g., priority tasks) so they never scroll out of view.