refactor: extract sanitizeForTestId to shared utility

Address PR review comments by:
- Creating shared sanitizeForTestId utility in apps/ui/src/lib/utils.ts
- Updating ProjectSwitcherItem to use the shared utility
- Adding matching helper to test utils for E2E tests
- Updating all E2E tests to use the sanitization helper

This ensures the component and tests use identical sanitization logic,
making tests robust against project names with special characters.

apps/ui/tests/utils/core/elements.ts

@@ -1,5 +1,22 @@
 import { Page, Locator } from '@playwright/test';
 
+/**
+ * Sanitize a string for use in data-testid selectors.
+ * This mirrors the sanitizeForTestId function in apps/ui/src/lib/utils.ts
+ * to ensure tests use the same sanitization logic as the component.
+ *
+ * @param name - The string to sanitize (e.g., project name)
+ * @returns A sanitized string safe for CSS selectors
+ */
+export function sanitizeForTestId(name: string): string {
+  return name
+    .toLowerCase()
+    .replace(/\s+/g, '-')
+    .replace(/[^a-z0-9-]/g, '')
+    .replace(/-+/g, '-')
+    .replace(/^-|-$/g, '');
+}
+
 /**
  * Get an element by its data-testid attribute
  */