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/hooks/__tests__/useWebhookForm.test.tsx

@@ -9,7 +9,7 @@ import { CREATE_WEBHOOK } from '@/settings/developers/graphql/mutations/createWe
 import { DELETE_WEBHOOK } from '@/settings/developers/graphql/mutations/deleteWebhook';
 import { UPDATE_WEBHOOK } from '@/settings/developers/graphql/mutations/updateWebhook';
 import { GET_WEBHOOK } from '@/settings/developers/graphql/queries/getWebhook';
-import { useWebhookForm } from '../useWebhookForm';
+import { useWebhookForm } from '@/settings/developers/hooks/useWebhookForm';
 
 const mockNavigateSettings = jest.fn();
 const mockEnqueueSuccessSnackBar = jest.fn();