fix(design-system): fix last table cell showing independent hover state (supabase#46251)

## What kind of change does this PR introduce?

Bug fix.

## What is the current behavior?

On pages where the table has horizontal overflow (e.g. Database Tables
with its 7 columns), `ShadowScrollArea` unconditionally applies
`!bg-surface-200` to `td:last-child` on row hover. Since `TableCell` has
`transition-colors`, this gives the last cell an explicit animated
background change — making it visually distinct from every other cell,
which simply inherit the row's hover bg transparently.

This manifests as the last cell appearing to have its own independent
hover state, separate from the row hover.

## What is the new behavior?

The `!bg-surface-200` override on `td:last-child` is moved inside the
`stickyLastColumn` block, since that's the only case where an explicit
background is actually needed (sticky cells require a solid bg to avoid
showing scrolled content behind them). Non-sticky tables no longer get
the spurious cell-level hover.

Also reverts the MoreVertical dropdown trigger in `TableList` back to
`type="default"` (undoes the workaround from supabase#46247).

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->

## Summary by CodeRabbit

* **Bug Fixes**
* Fixed hover styling behavior in horizontally scrollable tables to
apply only when appropriate.

* **Style**
  * Updated the visual appearance of the row action dropdown button.

<!-- review_stack_entry_start -->

[![Review Change
Stack](https://storage.googleapis.com/coderabbit_public_assets/review-stack-in-coderabbit-ui.svg)](https://app.coderabbit.ai/change-stack/supabase/supabase/pull/46251?utm_source=github_walkthrough&utm_medium=github&utm_campaign=change_stack)

<!-- review_stack_entry_end -->

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dnywh

apps/studio/components/interfaces/Database/Tables/TableList.tsx

@@ -493,7 +493,7 @@ export const TableList = ({
                             {!isSchemaLocked && (
                               <DropdownMenu>
                                 <DropdownMenuTrigger asChild>
-                                  <Button type="text" className="px-1" icon={<MoreVertical />} />
+                                  <Button type="default" className="px-1" icon={<MoreVertical />} />
                                 </DropdownMenuTrigger>
                                 <DropdownMenuContent side="bottom" align="end" className="w-40">
                                   <DropdownMenuItem

packages/ui/src/components/ShadowScrollArea/index.tsx

@@ -60,8 +60,8 @@ const ShadowScrollArea = React.forwardRef<HTMLDivElement, ShadowScrollAreaProps>
               '[&_tr:hover>*:last-child]:bg-transparent',
               '[&_th>*:last-child]:bg-surface-100',
               stickyColumnShadow,
+              hasHorizontalScroll && '[&_tr:hover>td:last-child]:!bg-surface-200',
             ],
-            hasHorizontalScroll && '[&_tr:hover>td:last-child]:!bg-surface-200',
             canScrollRight &&
               '[&_td]:before:opacity-100 [&_tr>*:last-child]:before:opacity-100 [&_th:last-child]:before:opacity-100',
             className