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/ui/feedback/snack-bar-manager/components/SnackBar.tsx

@@ -19,8 +19,11 @@ import {
 } from 'twenty-ui/display';
 import { ProgressBar, useProgressAnimation } from 'twenty-ui/feedback';
 import { LightButton, LightIconButton } from 'twenty-ui/input';
-import { ThemeContext } from 'twenty-ui/theme';
-import { MOBILE_VIEWPORT, themeCssVariables } from 'twenty-ui/theme-constants';
+import {
+  MOBILE_VIEWPORT,
+  ThemeContext,
+  themeCssVariables,
+} from 'twenty-ui/theme-constants';
 
 export enum SnackBarVariant {
   Default = 'default',
@@ -154,8 +157,8 @@ export const SnackBar = ({
   role = 'status',
   variant = SnackBarVariant.Default,
 }: SnackBarProps) => {
-  const { theme } = useContext(ThemeContext);
   const { i18n, t } = useLingui();
+  const { theme } = useContext(ThemeContext);
   const { animation: progressAnimation, value: progressValue } =
     useProgressAnimation({
       autoPlay: isUndefined(overrideProgressValue),
@@ -197,7 +200,7 @@ export const SnackBar = ({
           <IconAlertTriangle {...{ 'aria-label': ariaLabel, color, size }} />
         );
     }
-  }, [iconComponent, theme.icon.size.md, theme.snackBar, variant, i18n]);
+  }, [iconComponent, variant, i18n, theme.icon.size.md, theme.snackBar]);
 
   const handleMouseEnter = () => {
     if (progressAnimation?.state === 'running') {