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-ui/src/json-visualizer/components/internal/JsonArrow.tsx

@@ -2,7 +2,8 @@ import { styled } from '@linaria/react';
 import { VisibilityHidden } from '@ui/accessibility';
 import { IconChevronDown } from '@ui/display';
 import { useJsonTreeContextOrThrow } from '@ui/json-visualizer/hooks/useJsonTreeContextOrThrow';
-import { ICON_SIZES, themeCssVariables } from '@ui/theme-constants';
+import { ThemeContext, themeCssVariables } from '@ui/theme-constants';
+import { useContext } from 'react';
 import { motion } from 'framer-motion';
 
 const StyledButton = styled.button<{
@@ -38,6 +39,7 @@ export const JsonArrow = ({
   onClick: () => void;
   variant?: 'blue' | 'red';
 }) => {
+  const { theme } = useContext(ThemeContext);
   const { arrowButtonCollapsedLabel, arrowButtonExpandedLabel } =
     useJsonTreeContextOrThrow();
 
@@ -59,7 +61,7 @@ export const JsonArrow = ({
         animate={{ rotate: isOpen ? 0 : -90 }}
         transition={{ duration: 0.3 }}
       >
-        <IconChevronDown size={ICON_SIZES.md} color={iconColor} />
+        <IconChevronDown size={theme.icon.size.md} color={iconColor} />
       </motion.div>
     </StyledButton>
   );

packages/twenty-ui/src/json-visualizer/components/internal/JsonNodeLabel.tsx

@@ -1,8 +1,7 @@
 import { styled } from '@linaria/react';
 import { type IconComponent } from '@ui/display';
 import { type JsonNodeHighlighting } from '@ui/json-visualizer/types/JsonNodeHighlighting';
-import { ThemeContext } from '@ui/theme';
-import { themeCssVariables } from '@ui/theme-constants';
+import { ThemeContext, themeCssVariables } from '@ui/theme-constants';
 import { useContext } from 'react';
 
 const StyledLabelContainer = styled.span<{