fix: add retry logic and npm cache cleanup for Windows tests

- Clear npm cache on Windows before tests to avoid lock corruption
- Add retry logic (3 attempts) for CLI test to handle transient issues
- Use nick-fields/retry@v3 action for robust test execution

This addresses intermittent npm cache corruption errors on Windows runners.

Fixes #4

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

Author: claude

.github/workflows/test.yml

@@ -86,8 +86,18 @@ jobs:
       - name: Install package
         run: uv sync
 
+      - name: Clear npm cache on Windows
+        if: runner.os == 'Windows'
+        run: npm cache clean --force
+        continue-on-error: true
+
       - name: Test CLI can be invoked
-        run: uv run promptfoo --version
+        uses: nick-fields/retry@v3
+        with:
+          timeout_minutes: 3
+          max_attempts: 3
+          retry_on: error
+          command: uv run promptfoo --version
 
       - name: Test Node.js detection
         run: uv run python -c "from promptfoo.cli import check_node_installed, check_npx_installed; assert check_node_installed(); assert check_npx_installed()"