feat(branding): rebrand footer vendor to MesaStack, trim footer/topbar

- Footer vendor label unified to "MesaStack" across all locales.
- Remove footer Help button; keep version as plain text (no click).
- Remove top-right GitHub star widget (delete unused github-star.tsx);
  keep version as plain text (no click), retain upgrade "New" badge.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/layouts/extraRender.tsx

@@ -1,8 +1,6 @@
 import { GPUStackVersionAtom, UpdateCheckAtom } from '@/atoms/user';
 import PluginExtraField from '@/components/plugin-extra-fields';
-import VersionInfo, { modalConfig } from '@/components/version-info';
 import externalLinks from '@/constants/external-links';
-import useBodyScroll from '@/hooks/use-body-scroll';
 import { logout } from '@/pages/login/apis';
 import { useModel } from '@@/plugin-model';
 import {
@@ -13,12 +11,11 @@ import {
 } from '@ant-design/icons';
 import { DropdownActions, IconFont } from '@gpustack/core-ui';
 import { history, useIntl, useNavigate } from '@umijs/max';
-import { Avatar, Button, Divider, Modal } from 'antd';
+import { Avatar, Divider } from 'antd';
 import { useAtom } from 'jotai';
 import { useMemo } from 'react';
 import styled from 'styled-components';
 import { DEFAULT_ENTER_PAGE } from '../config/settings';
-import GithubStar from './github-star';
 
 const NewLabel = styled.span`
   position: relative;
@@ -98,11 +95,9 @@ const CustomItem = styled.div`
 
 export const ExtraContent = (props: { isDarkTheme?: boolean }) => {
   const { isDarkTheme } = props;
-  const { saveScrollHeight, restoreScrollHeight } = useBodyScroll();
-  const [modal, contextHolder] = Modal.useModal();
+  const intl = useIntl();
   const [version] = useAtom(GPUStackVersionAtom);
   const [updateCheck] = useAtom(UpdateCheckAtom);
-  const intl = useIntl();
   const initialInfo = useModel('@@initialState') || {
     initialState: undefined,
     loading: false,
@@ -140,16 +135,6 @@ export const ExtraContent = (props: { isDarkTheme?: boolean }) => {
     return {};
   }, [isDarkTheme]);
 
-  const showVersion = () => {
-    saveScrollHeight();
-    modal.info({
-      ...modalConfig,
-      width: 460,
-      content: <VersionInfo intl={intl} />,
-      onCancel: restoreScrollHeight
-    });
-  };
-
   const handleLogout = async () => {
     await logout();
     navigate(loginPath);
@@ -259,25 +244,20 @@ export const ExtraContent = (props: { isDarkTheme?: boolean }) => {
 
   return (
     <Wrapper>
-      {contextHolder}
       <PluginExtraField name="OrgSwitcher" isDarkTheme={isDarkTheme} />
-      {process.env.ENABLE_ENTERPRISE !== 'true' && <GithubStar />}
       <div
         style={{
           display: 'flex',
           alignItems: 'center'
         }}
       >
-        <Button
-          type="text"
-          size="small"
-          onClick={showVersion}
+        <span
           style={{
             color: 'var(--ant-color-text-tertiary)'
           }}
         >
           {version.version}
-        </Button>
+        </span>
         {showUpgrade && (
           <NewLabel>
             <span className="text">