chore(twenty-front): migrate auth, activities, AI, pages and small modules from Emotion to Linaria (PR 2-3/10) (#18328)

## Summary

- Migrate ~200 files from `@emotion/styled` / `@emotion/react` to
`@linaria/react` + `themeCssVariables`, continuing the zero-runtime
CSS-in-JS migration (PR 2-3 of the [migration
plan](docs/emotion-to-linaria-migration-plan.md))
- Modules covered: **auth** (19), **activities** (53), **ai** (30),
**pages** (70), **action-menu** (3), **object-metadata** (4),
**onboarding** (2), **workspace** (2), **file** (3), **error-handler**
(2), **front-components** (1), **geo-map** (1), **loading** (5),
**testing** (5), plus a `style` prop addition to `TableRow`
- Handles `styled(FunctionComponent)<Props>` incompatibility with
Linaria by using CSS custom properties via `style` + `var()` references

## Test plan

- [x] `npx nx lint:diff-with-main twenty-front` passes
- [x] `npx nx typecheck twenty-front` passes
- [ ] Visual spot-check of auth, onboarding, settings, activities, and
AI chat screens
- [ ] No remaining `@emotion/styled` or `@emotion/react` imports in
migrated files


Made with [Cursor](https://cursor.com)

packages/twenty-front/src/loading/components/MainNavigationDrawerItemsSkeletonLoader.tsx

@@ -1,7 +1,8 @@
 import { SKELETON_LOADER_HEIGHT_SIZES } from '@/activities/components/SkeletonLoader';
-import { useTheme } from '@emotion/react';
-import styled from '@emotion/styled';
+import { styled } from '@linaria/react';
+import { useContext } from 'react';
 import Skeleton, { SkeletonTheme } from 'react-loading-skeleton';
+import { ThemeContext } from 'twenty-ui/theme';
 
 const StyledSkeletonContainer = styled.div`
   align-items: flex-start;
@@ -20,7 +21,7 @@ export const MainNavigationDrawerItemsSkeletonLoader = ({
   title?: boolean;
   length: number;
 }) => {
-  const theme = useTheme();
+  const { theme } = useContext(ThemeContext);
 
   return (
     <StyledSkeletonContainer>