fix(site): restore chat search dialog position (#28900)

> 🤖 This PR was written by Coder Agents on behalf of Jake Howell.

Tailwind CSS 4 emits translation utilities through the individual
`translate` property, so the chat search dialog's custom `transform` no
longer canceled the inherited vertical translation and left the dialog
incorrectly positioned.

Restore the intended positioning with `translate-y-0`, preserving the
shared horizontal centering while disabling vertical centering.


| Old | New |
| --- | --- |
| <img width="1624" height="1061" alt="image"
src="https://github.com/user-attachments/assets/a657a90e-0b8f-473a-bbea-39be083e602f"
/> | <img width="1624" height="1061" alt="image"
src="https://github.com/user-attachments/assets/a5ada6e0-0fb9-4172-a4e2-74298dc64c03"
/> |

site/src/pages/AgentsPage/components/ChatsSidebar/dialogs/ChatSearchDialog.tsx

@@ -101,7 +101,7 @@ export const ChatSearchDialog: FC<ChatSearchDialogProps> = ({
 				// input + gap-4 + summary + space-y-3 + the 300px scroll area in
 				// ChatSearchResults). The max(1rem, ...) clamp keeps the dialog
 				// fully visible on short viewports.
-				className="top-[max(1rem,calc(50%-218px))] w-[calc(100vw-2rem)] max-w-[560px] [transform:translateX(-50%)] gap-4 border-border-default bg-surface-primary p-6 sm:p-6"
+				className="top-[max(1rem,calc(50%-218px))] w-[calc(100vw-2rem)] max-w-[560px] translate-y-0 gap-4 border-border-default bg-surface-primary p-6 sm:p-6"
 				// Suppress the open/close animation. The `animate-in`/`animate-out`
 				// rules applied via CVA in `dialogVariants` outrank Tailwind class
 				// overrides, so we disable them with an inline style to avoid the