fix: treat pytest exit code 5 (no tests) as success

CI was failing because no tests exist yet. Exit code 5 means
"no tests collected" — valid during early setup before Day 3.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: prithaxdev

.github/workflows/ci.yml

@@ -28,4 +28,4 @@ jobs:
         run: pip install -e ".[dev]"
 
       - name: Run tests
-        run: pytest -v
+        run: pytest -v || [ $? -eq 5 ]