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/utils/__tests__/date-utils.test.ts

@@ -12,8 +12,8 @@ import {
   beautifyPastDateRelativeToNow,
   hasDatePassed,
   parseDate,
-} from '../date-utils';
-import { logError } from '../logError';
+} from '~/utils/date-utils';
+import { logError } from '~/utils/logError';
 
 i18n.load(SOURCE_LOCALE, enMessages);
 i18n.activate(SOURCE_LOCALE);