fix(cli): add cross-platform support for critical system directory protection

- Create safe-paths utility with platform-specific critical path detection
- Support Windows (C:\, C:\Windows, C:\Program Files, etc)
- Support macOS (/, /System, /Library, /Applications, etc)
- Support Linux (/, /usr, /etc, /var, /root, etc)
- Refactor install and update commands to use new utility
- Add comprehensive test suite (11 tests covering all platforms)

Fixes: POSIX path handling that failed on Windows

Author: cleberhensel

apps/cli/src/utils/__tests__/safe-paths.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, beforeEach, afterEach } from 'vitest';
+import { describe, it, expect, afterEach } from 'vitest';
 import { getCriticalSystemPaths, isCriticalSystemDirectory, isUserHomeDirectory } from '../safe-paths.js';
 import os from 'node:os';
 import path from 'node:path';