feat: enforce @/ alias for imports and fix all relative parent imports (#16787)

## Summary
This PR enforces the use of `@/` alias for imports instead of relative
parent imports (`../`).

## Changes

### ESLint Configuration
- Added `no-restricted-imports` pattern in `eslint.config.react.mjs` to
block `../*` imports with the message "Relative parent imports are not
allowed. Use @/ alias instead."
- Removed the non-working `import/no-relative-parent-imports` rule
(doesn't work properly in ESLint flat config)

### VS Code Settings
- Added `javascript.preferences.importModuleSpecifier: non-relative` to
`.vscode/settings.json` (TypeScript setting was already there)

### Code Fixes
- Fixed **941 relative parent imports** across **706 files** in
`packages/twenty-front`
- All `../` imports converted to use `@/` alias

## Why
- Consistent import style across the codebase
- Easier to move files without breaking imports
- Better IDE support for auto-imports
- Clearer understanding of where imports come from

packages/twenty-front/src/testing/decorators/ComponentWithRouterDecorator.tsx

@@ -12,7 +12,7 @@ import {
   isRouteParams,
 } from '~/testing/decorators/PageDecorator';
 
-import { ComponentStorybookLayout } from '../ComponentStorybookLayout';
+import { ComponentStorybookLayout } from '~/testing/ComponentStorybookLayout';
 
 interface StrictArgs {
   [name: string]: unknown;

packages/twenty-front/src/testing/decorators/I18nFrontDecorator.tsx

@@ -1,7 +1,7 @@
 import { i18n } from '@lingui/core';
 import { I18nProvider } from '@lingui/react';
 import { type Decorator } from '@storybook/react';
-import { messages as enMessages } from '../../locales/generated/en';
+import { messages as enMessages } from '~/locales/generated/en';
 import { SOURCE_LOCALE } from 'twenty-shared/translations';
 
 i18n.load({

packages/twenty-front/src/testing/decorators/PageDecorator.tsx

@@ -33,7 +33,7 @@ import { I18nProvider } from '@lingui/react';
 import { SOURCE_LOCALE } from 'twenty-shared/translations';
 import { IconsProvider } from 'twenty-ui/display';
 import { dynamicActivate } from '~/utils/i18n/dynamicActivate';
-import { FullHeightStorybookLayout } from '../FullHeightStorybookLayout';
+import { FullHeightStorybookLayout } from '~/testing/FullHeightStorybookLayout';
 
 export type PageDecoratorArgs = {
   routePath: string;

packages/twenty-front/src/testing/decorators/RootDecorator.tsx

@@ -4,7 +4,7 @@ import { RecoilRoot } from 'recoil';
 
 import { ApolloCoreClientMockedProvider } from '@/object-metadata/hooks/__mocks__/ApolloCoreClientMockedProvider';
 
-import { mockedApolloClient } from '../mockedApolloClient';
+import { mockedApolloClient } from '~/testing/mockedApolloClient';
 
 export const RootDecorator: Decorator = (Story, context) => {
   const { parameters } = context;