Deprecate runtime theme objects in favor of CSS variables (#18402)

## Summary

- **Eliminate `ICON_SIZES` / `ICON_STROKES` constants**: all icon
dimensions are now resolved at runtime via
`resolveThemeVariableAsNumber(themeCssVariables.icon.size.X)`, ensuring
values always come from computed CSS variables
- **No more consumer imports from `twenty-ui/theme`**: moved
`ColorSchemeContext`, `ColorSchemeProvider`, `ThemeColor`,
`MAIN_COLOR_NAMES`, `getNextThemeColor`, `AnimationDuration` to
`twenty-ui/theme-constants`
- **Remove `ThemeContext` / `ThemeContextProvider` / `ThemeProvider` /
`ThemeType`**: replaced across ~300 files with `themeCssVariables` (for
CSS contexts) or `resolveThemeVariable` / `resolveThemeVariableAsNumber`
(for JS runtime values)
- **Simplify provider chain**: only `ColorSchemeProvider` remains — it
toggles `light`/`dark` class on `document.documentElement` and provides
`colorScheme` via React context
- **Fix pre-existing test failures**: `useIcons.test.ts`
(non-configurable ES module spy) and
`turnRecordFilterGroupIntoGqlOperationFilter.test.ts`
(`Omit<RecordFilter, 'id'>` type mismatch)

### Theme access pattern (before → after)

| Context | Before | After |
|---------|--------|-------|
| CSS (Linaria) | `${({ theme }) => theme.font.color.primary}` |
`${themeCssVariables.font.color.primary}` |
| JS runtime (icon size, animation) | `theme.icon.size.md` /
`ICON_SIZES.md` |
`resolveThemeVariableAsNumber(themeCssVariables.icon.size.md)` |
| Color scheme check | `theme.name === 'dark'` |
`useContext(ColorSchemeContext).colorScheme === 'dark'` |

packages/twenty-front/src/modules/settings/data-model/objects/components/SettingsDataModelObjectSummary.tsx

@@ -1,6 +1,6 @@
 import { t } from '@lingui/core/macro';
-import { useContext } from 'react';
 import { styled } from '@linaria/react';
+import { useContext } from 'react';
 
 import { type ObjectMetadataItem } from '@/object-metadata/types/ObjectMetadataItem';
 import {
@@ -9,8 +9,7 @@ import {
   useIcons,
 } from 'twenty-ui/display';
 import { SettingsItemTypeTag } from '@/settings/components/SettingsItemTypeTag';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 
 export type SettingsDataModelObjectPreviewProps = {
   className?: string;
@@ -103,6 +102,7 @@ const SettingsDataModelObjectPreviewOtherObjects = ({
   selected: number;
 }) => {
   const { theme } = useContext(ThemeContext);
+
   return (
     <>
       <StyledSeparator />

packages/twenty-front/src/modules/settings/data-model/objects/components/SettingsObjectCoverImage.tsx

@@ -10,9 +10,7 @@ import { Card } from 'twenty-ui/layout';
 
 import DarkCoverImage from '@/settings/data-model/assets/cover-dark.png';
 import LightCoverImage from '@/settings/data-model/assets/cover-light.png';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
-
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 const StyledCoverImageContainer = styled(Card)`
   align-items: center;
   background-size: cover;
@@ -29,13 +27,14 @@ const StyledButtonContainer = styled.div`
   padding-top: ${themeCssVariables.spacing[5]};
 `;
 export const SettingsObjectCoverImage = () => {
+  const { colorScheme } = useContext(ThemeContext);
+
   const { t } = useLingui();
-  const { theme } = useContext(ThemeContext);
   return (
     <StyledCoverImageContainer
       style={{
         backgroundImage:
-          theme.name === 'light'
+          colorScheme === 'light'
             ? `url('${LightCoverImage.toString()}')`
             : `url('${DarkCoverImage.toString()}')`,
       }}

packages/twenty-front/src/modules/settings/data-model/objects/forms/components/SettingsDataModelObjectAboutForm.tsx

@@ -6,8 +6,8 @@ import { type SettingsDataModelObjectAboutFormValues } from '@/settings/data-mod
 import { IconPicker } from '@/ui/input/components/IconPicker';
 import { SettingsTextInput } from '@/ui/input/components/SettingsTextInput';
 import { TextArea } from '@/ui/input/components/TextArea';
-import { useContext } from 'react';
 import { styled } from '@linaria/react';
+import { useContext } from 'react';
 import { useLingui } from '@lingui/react/macro';
 import { plural } from 'pluralize';
 import { Controller, useFormContext } from 'react-hook-form';
@@ -22,8 +22,7 @@ import {
 } from 'twenty-ui/display';
 import { Button } from 'twenty-ui/input';
 import { Card } from 'twenty-ui/layout';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 import { type StringKeyOf } from 'type-fest';
 import { useNavigateSettings } from '~/hooks/useNavigateSettings';
 import { computeMetadataNameFromLabel } from '~/pages/settings/data-model/utils/computeMetadataNameFromLabel';
@@ -115,10 +114,10 @@ export const SettingsDataModelObjectAboutForm = ({
   objectMetadataItem,
   conflictingObjectMetadataItem,
 }: SettingsDataModelObjectAboutFormProps) => {
+  const { theme } = useContext(ThemeContext);
   const { control, watch, setValue } =
     useFormContext<SettingsDataModelObjectAboutFormValues>();
   const { t } = useLingui();
-  const { theme } = useContext(ThemeContext);
   const navigateSettings = useNavigateSettings();
 
   const isLabelSyncedWithName = watch('isLabelSyncedWithName');