Complete linaria migration (#18361)

## Summary

Completes the migration of the frontend styling system from **Emotion**
(`@emotion/styled`, `@emotion/react`) to **Linaria** (`@linaria/react`,
`@linaria/core`), a zero-runtime CSS-in-JS library where styles are
extracted at build time.

This is the final step of the migration — all ~494 files across
`twenty-front`, `twenty-ui`, `twenty-website`, and `twenty-sdk` are now
fully converted.

## Changes

### Styling Migration (across ~480 component files)
- Replaced all `@emotion/styled` imports with `@linaria/react`
- Converted runtime theme access patterns (`({ theme }) => theme.x.y`)
to build-time `themeCssVariables` CSS custom properties
- Replaced `useTheme()` hook (from Emotion) with
`useContext(ThemeContext)` where runtime theme values are still needed
(e.g., passing colors to non-CSS props like icon components)
- Removed `@emotion/react` `css` helper usages in favor of Linaria
template literals

### Dependency & Configuration Changes
- **Removed**: `@emotion/react`, `@emotion/styled` from root
`package.json`
- **Added**: `@wyw-in-js/babel-preset`, `next-with-linaria` (for
twenty-website SSR support)
- Updated Nx generator defaults from `@emotion/styled` to
`@linaria/react` in `nx.json`
- Simplified `vite.config.ts` (removed Emotion-specific configuration)
- Updated `twenty-website/next.config.js` to use `next-with-linaria` for
SSR Linaria support

### Storybook & Testing
- Removed `ThemeProvider` from Emotion in Storybook previews
(`twenty-front`, `twenty-sdk`)
- Now relies solely on `ThemeContextProvider` for theme injection

### Documentation
- Removed the temporary `docs/emotion-to-linaria-migration-plan.md`
(migration complete)
- Updated `CLAUDE.md` and `README.md` to reflect Linaria as the styling
stack
- Updated frontend style guide docs across all locales

## How it works

Linaria extracts styles at build time via the `@wyw-in-js/vite` plugin.
All expressions in `styled` template literals must be **statically
evaluable** — no runtime theme objects or closures over component state.

- **Static styles** use `themeCssVariables` which map to CSS custom
properties (`var(--theme-color-x)`)
- **Runtime theme access** (for non-CSS use cases like icon `color`
props) uses `useContext(ThemeContext)` instead of Emotion's `useTheme()`

packages/twenty-front/src/modules/settings/data-model/new-object/components/SettingsAvailableStandardObjectItemTableRow.tsx

@@ -1,11 +1,13 @@
-import { useTheme } from '@emotion/react';
-import styled from '@emotion/styled';
+import { useContext } from 'react';
+import { styled } from '@linaria/react';
 
 import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
 import { TableCell } from '@/ui/layout/table/components/TableCell';
 import { TableRow } from '@/ui/layout/table/components/TableRow';
 import { Checkbox } from 'twenty-ui/input';
 import { useIcons } from 'twenty-ui/display';
+import { ThemeContext } from 'twenty-ui/theme';
+import { themeCssVariables } from 'twenty-ui/theme-constants';
 
 type SettingsAvailableStandardObjectItemTableRowProps = {
   isSelected?: boolean;
@@ -20,12 +22,12 @@ export const StyledAvailableStandardObjectTableRow = styled(TableRow)`
 const StyledCheckboxTableCell = styled(TableCell)`
   justify-content: center;
   padding: 0;
-  padding-left: ${({ theme }) => theme.spacing(1)};
+  padding-left: ${themeCssVariables.spacing[1]};
 `;
 
 const StyledNameTableCell = styled(TableCell)`
-  color: ${({ theme }) => theme.font.color.primary};
-  gap: ${({ theme }) => theme.spacing(2)};
+  color: ${themeCssVariables.font.color.primary};
+  gap: ${themeCssVariables.spacing[2]};
 `;
 
 const StyledDescription = styled.div`
@@ -39,7 +41,7 @@ export const SettingsAvailableStandardObjectItemTableRow = ({
   objectItem,
   onClick,
 }: SettingsAvailableStandardObjectItemTableRowProps) => {
-  const theme = useTheme();
+  const { theme } = useContext(ThemeContext);
 
   const { getIcon } = useIcons();
   const Icon = getIcon(objectItem.icon);