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/activities/files/components/AttachmentRow.tsx

@@ -10,7 +10,7 @@ import {
 import { getFileCategoryFromExtension } from '@/object-record/record-field/ui/utils/getFileCategoryFromExtension';
 import { SettingsTextInput } from '@/ui/input/components/SettingsTextInput';
 import { styled } from '@linaria/react';
-import { useContext, useState } from 'react';
+import { useState, useContext } from 'react';
 import { isDefined } from 'twenty-shared/utils';
 
 import { type AttachmentWithFile } from '@/activities/files/utils/filterAttachmentsWithFile';
@@ -18,8 +18,7 @@ import { FileIcon } from '@/file/components/FileIcon';
 import { useHasPermissionFlag } from '@/settings/roles/hooks/useHasPermissionFlag';
 import { CoreObjectNameSingular } from 'twenty-shared/types';
 import { IconCalendar, OverflowingTextWithTooltip } from 'twenty-ui/display';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 import { isNavigationModifierPressed } from 'twenty-ui/utilities';
 import { PermissionFlagType } from '~/generated-metadata/graphql';
 import { formatToHumanReadableDate } from '~/utils/date-utils';

packages/twenty-front/src/modules/activities/files/components/DocumentViewer.tsx

@@ -13,8 +13,7 @@ import { useContext, useEffect, useState } from 'react';
 import { isDefined } from 'twenty-shared/utils';
 import { IconDownload } from 'twenty-ui/display';
 import { Button } from 'twenty-ui/input';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 import { getFileNameAndExtension } from '~/utils/file/getFileNameAndExtension';
 
 const MS_OFFICE_EXTENSIONS = [
@@ -200,8 +199,8 @@ export const DocumentViewer = ({
   documentUrl,
   documentExtension,
 }: DocumentViewerProps) => {
-  const { t } = useLingui();
   const { theme } = useContext(ThemeContext);
+  const { t } = useLingui();
   const [csvPreview, setCsvPreview] = useState<CsvPreviewData | undefined>(
     undefined,
   );

packages/twenty-front/src/modules/activities/files/components/DropZone.tsx

@@ -1,12 +1,11 @@
-import { useContext } from 'react';
 import { styled } from '@linaria/react';
 import { useLingui } from '@lingui/react/macro';
+import { useContext } from 'react';
 import { useDropzone } from 'react-dropzone';
 
 import { useSpreadsheetImportInternal } from '@/spreadsheet-import/hooks/useSpreadsheetImportInternal';
 import { IconUpload } from 'twenty-ui/display';
-import { ThemeContext } from 'twenty-ui/theme';
-import { themeCssVariables } from 'twenty-ui/theme-constants';
+import { ThemeContext, themeCssVariables } from 'twenty-ui/theme-constants';
 
 const StyledContainer = styled.div`
   align-items: center;
@@ -49,8 +48,8 @@ export const DropZone = ({
   setIsDraggingFile,
   onUploadFiles,
 }: DropZoneProps) => {
-  const { t } = useLingui();
   const { theme } = useContext(ThemeContext);
+  const { t } = useLingui();
   const { maxFileSize } = useSpreadsheetImportInternal();
 
   const { getRootProps, getInputProps, isDragActive } = useDropzone({