fix: absolute positioning of button and enable select all rows (marimo-team#5643)

## 📝 Summary

<!--
Provide a concise summary of what this pull request is addressing.

If this PR fixes any issues, list them here by number (e.g., Fixes
marimo-team#123).
-->

- fixes absolute positioning of delete rows button
- enable select and deselect all rows

Previously:
<img width="600" alt="CleanShot 2025-07-15 at 23 06 19"
src="https://github.com/user-attachments/assets/f2a17dd2-718b-4c77-a5f3-187b0891b01f"
/>

Now:
<img width="600" alt="CleanShot 2025-07-15 at 23 05 26"
src="https://github.com/user-attachments/assets/87391c88-fa3f-470f-b077-5eef4219172d"
/>


## 🔍 Description of Changes

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problem addressed and how it was resolved. If applicable, provide before
and after comparisons, screenshots, or any relevant details to help
reviewers understand the changes easily.
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## 📋 Checklist

- [x] I have read the [contributor
guidelines](https://github.com/marimo-team/marimo/blob/main/CONTRIBUTING.md).
- [ ] For large changes, or changes that affect the public API: this
change was discussed or approved through an issue, on
[Discord](https://marimo.io/discord?ref=pr), or the community
[discussions](https://github.com/marimo-team/marimo/discussions) (Please
provide a link if applicable).
- [ ] I have added tests for the changes made.
- [x] I have run the code and verified that it works as expected.

Author: Light2Dark

frontend/src/plugins/impl/data-editor/glide-data-editor.tsx

@@ -572,7 +572,7 @@ export const GlideDataEditor = <T,>({
   };
 
   return (
-    <>
+    <div className="relative">
       <ErrorBoundary>
         <DataEditor
           ref={dataEditorRef}
@@ -595,7 +595,6 @@ export const GlideDataEditor = <T,>({
           width={"100%"}
           rowMarkers={{
             kind: "both",
-            headerDisabled: true,
           }}
           rowSelectionMode={"multi"}
           onCellEdited={onCellEdited}
@@ -615,13 +614,13 @@ export const GlideDataEditor = <T,>({
           variant="destructive"
           size="sm"
           disabled={selection.rows.length === 0}
-          className="bottom-1 right-2 h-7"
+          className="right-2 h-7"
           onClick={handleDeleteRows}
         >
           {selection.rows.length <= 1 ? "Delete row" : "Delete rows"}
         </Button>
       </div>
-    </>
+    </div>
   );
 };