chore(twenty-front): migrate small modules from Emotion to Linaria (PR 1/10) (#18314)

## Emotion → Linaria migration — PR 1 of 10

First batch of the `twenty-front` migration from Emotion (runtime
CSS-in-JS) to Linaria (zero-runtime, build-time extraction via
wyw-in-js). Covers **100 files** across 10 small standalone modules —
chosen as the lowest-risk starting point.

### Modules migrated

spreadsheet-import (28) · navigation-menu-item (17) · views (14) ·
billing (10) · blocknote-editor (7) · advanced-text-editor (7) ·
favorites (7) · navigation (4) · information-banner (3) ·
sign-in-background-mock (3)

### Migration pattern

Every file follows the same mechanical transformation:

| Emotion | Linaria |
|---|---|
| `import styled from '@emotion/styled'` | `import { styled } from
'@linaria/react'` |
| `${({ theme }) => theme.font.color.primary}` |
`${themeCssVariables.font.color.primary}` |
| `${({ theme }) => theme.spacing(4)}` |
`${themeCssVariables.spacing[4]}` |
| `const theme = useTheme()` | `const { theme } =
useContext(ThemeContext)` |
| `import { type Theme } from '@emotion/react'` | `import { type
ThemeType } from 'twenty-ui/theme'` |

`themeCssVariables` is a build-time object where every leaf is a
`var(--t-xxx)` CSS custom property reference, evaluated statically by
wyw-in-js. Runtime theme access (icon sizes, colors passed as props)
uses `useContext(ThemeContext)`.

### Gotchas encountered & fixed

- **Interpolation return types** — wyw-in-js requires `string | number`,
never `false`/`undefined`. Replaced `condition && 'css'` with `condition
? 'css' : ''`.
- **`css` tag inside `styled` templates** — Linaria `css` returns a
class name, not CSS text. Replaced with plain template strings.
- **`styled(Component)` needs `className`** — added `className` prop to
`NavigationDrawerSection`, `DropdownMenuItemsContainer`, and `Heading`.
- **`shouldForwardProp` not supported** — Linaria filters invalid DOM
props automatically for HTML elements. For custom components, used
wrapper divs where needed.
- **`FormFieldPlaceholderStyles`** — converted from Emotion `css`
function to a static string using `themeCssVariables`.

packages/twenty-front/src/modules/advanced-text-editor/components/AdvancedTextEditor.tsx

@@ -2,8 +2,9 @@ import { ImageBubbleMenu } from '@/advanced-text-editor/components/ImageBubbleMe
 import { LinkBubbleMenu } from '@/advanced-text-editor/components/LinkBubbleMenu';
 import { TextBubbleMenu } from '@/advanced-text-editor/components/TextBubbleMenu';
 import { FORM_FIELD_PLACEHOLDER_STYLES } from '@/object-record/record-field/ui/form-types/constants/FormFieldPlaceholderStyles';
-import styled from '@emotion/styled';
+import { styled } from '@linaria/react';
 import { EditorContent, type Editor } from '@tiptap/react';
+import { themeCssVariables } from 'twenty-ui/theme-constants';
 
 const StyledEditorContainer = styled.div<{
   readonly?: boolean;
@@ -24,14 +25,16 @@ const StyledEditorContainer = styled.div<{
   }
 
   .tiptap {
-    padding: ${({ theme }) => `${theme.spacing(1)} ${theme.spacing(2)}`};
+    padding: ${themeCssVariables.spacing[1]} ${themeCssVariables.spacing[2]};
     box-sizing: border-box;
     height: 100%;
-    color: ${({ theme, readonly }) =>
-      readonly ? theme.font.color.light : theme.font.color.primary};
-    font-family: ${({ theme }) => theme.font.family};
-    font-size: ${({ theme }) => theme.font.size.sm};
-    font-weight: ${({ theme }) => theme.font.weight.regular};
+    color: ${({ readonly }) =>
+      readonly
+        ? themeCssVariables.font.color.light
+        : themeCssVariables.font.color.primary};
+    font-family: ${themeCssVariables.font.family};
+    font-size: ${themeCssVariables.font.size.sm};
+    font-weight: ${themeCssVariables.font.weight.regular};
     border: none !important;
 
     p.is-editor-empty:first-of-type::before {
@@ -48,10 +51,10 @@ const StyledEditorContainer = styled.div<{
     }
 
     .variable-tag {
-      background-color: ${({ theme }) => theme.color.blue3};
-      border-radius: ${({ theme }) => theme.border.radius.sm};
-      color: ${({ theme }) => theme.color.blue};
-      padding: ${({ theme }) => theme.spacing(1)};
+      background-color: ${themeCssVariables.color.blue3};
+      border-radius: ${themeCssVariables.border.radius.sm};
+      color: ${themeCssVariables.color.blue};
+      padding: ${themeCssVariables.spacing[1]};
     }
 
     h1 {
@@ -67,7 +70,7 @@ const StyledEditorContainer = styled.div<{
     }
 
     li {
-      margin-bottom: ${({ theme }) => theme.spacing(2)};
+      margin-bottom: ${themeCssVariables.spacing[2]};
       line-height: 1.5;
     }
   }