refactor: remove introductory access banner from /agents page (#27865)

## Summary

Removes the "Introductory access to Coder Agents through September 2026"
text and its now-unused `docs` import from the `/agents` page
(`AgentCreateForm.tsx`).

## Changes

- Removed the `<p>` element containing the introductory access link and
text below the chat input
- Removed the now-unused `docs` import (it was only referenced by that
link)

## Testing

No stories or tests referenced the removed text, so no test updates are
needed.

---

PR generated with Coder Agents

site/src/pages/AgentsPage/components/AgentCreateForm.tsx

@@ -9,7 +9,6 @@ import { Alert, AlertDescription, AlertTitle } from "#/components/Alert/Alert";
 import { ErrorAlert } from "#/components/Alert/ErrorAlert";
 import { ConfirmDialog } from "#/components/Dialog/ConfirmDialog/ConfirmDialog";
 import { useDashboard } from "#/modules/dashboard/useDashboard";
-import { docs } from "#/utils/docs";
 import { useFileAttachments } from "../hooks/useFileAttachments";
 import { parseStoredDraft } from "../utils/draftStorage";
 import {
@@ -613,17 +612,6 @@ export const AgentCreateForm: FC<AgentCreateFormProps> = ({
 							{modelSelectorHelp}
 						</div>
 					) : null}
-					<p className="text-center text-xs text-content-secondary/50">
-						<a
-							href={docs("/ai-coder/agents")}
-							target="_blank"
-							rel="noreferrer"
-							className="text-content-secondary/50 underline hover:text-content-secondary"
-						>
-							Introductory access
-						</a>{" "}
-						to Coder Agents through September 2026
-					</p>
 				</div>
 			</div>
 			<ConfirmDialog