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/modules/settings/developers/utils/__tests__/addEmptyOperationIfNecessary.test.ts

@@ -1,6 +1,6 @@
 import { WEBHOOK_EMPTY_OPERATION } from '~/pages/settings/developers/webhooks/constants/WebhookEmptyOperation';
 import { type WebhookOperationType } from '~/pages/settings/developers/webhooks/types/WebhookOperationsType';
-import { addEmptyOperationIfNecessary } from '../addEmptyOperationIfNecessary';
+import { addEmptyOperationIfNecessary } from '@/settings/developers/utils/addEmptyOperationIfNecessary';
 
 describe('addEmptyOperationIfNecessary', () => {
   it('should add empty operation when no wildcard or null object operations exist', () => {

packages/twenty-front/src/modules/settings/developers/utils/__tests__/cleanAndFormatOperations.test.ts

@@ -1,5 +1,5 @@
 import { type WebhookOperationType } from '~/pages/settings/developers/webhooks/types/WebhookOperationsType';
-import { cleanAndFormatOperations } from '../cleanAndFormatOperations';
+import { cleanAndFormatOperations } from '@/settings/developers/utils/cleanAndFormatOperations';
 
 describe('cleanAndFormatOperations', () => {
   it('should filter out operations with null object values', () => {

packages/twenty-front/src/modules/settings/developers/utils/__tests__/createWebhookInput.test.ts

@@ -2,7 +2,7 @@ import { type WebhookFormValues } from '@/settings/developers/validation-schemas
 import {
   createWebhookCreateInput,
   createWebhookUpdateInput,
-} from '../createWebhookInput';
+} from '@/settings/developers/utils/createWebhookInput';
 
 describe('createWebhookInput', () => {
   const mockFormValues: WebhookFormValues = {

packages/twenty-front/src/modules/settings/developers/utils/__tests__/parseOperationsFromStrings.test.ts

@@ -1,4 +1,4 @@
-import { parseOperationsFromStrings } from '../parseOperationsFromStrings';
+import { parseOperationsFromStrings } from '@/settings/developers/utils/parseOperationsFromStrings';
 
 describe('parseOperationsFromStrings', () => {
   it('should parse operation strings into object/action pairs', () => {