[haik]: refactor: reorganize backend/tests/test_cases from flat structure into domain subdirectories — moved 36 test files into auth/, browser/, labeling/, service/, settings/, and web_search/ for better discoverability and grouping

backend/tests/test_cases/service/test_disconnect_resilience.py

@@ -22,7 +22,7 @@ message, completed). That keeps the test fast (>200 iterations in
 seconds) and self-contained.
 
 Run:
-    cd backend && .venv/bin/python -m pytest tests/test_disconnect_resilience.py -v
+    cd backend && .venv/bin/python -m pytest tests/test_cases/service/test_disconnect_resilience.py -v
 """
 
 from __future__ import annotations

backend/tests/test_cases/service/test_service.py

@@ -10,7 +10,7 @@ opaque dicts; the cloud determines what they are. Tests verify:
   - Legacy shims (submit, record, identify) route through sync
 
 Run:
-    cd backend && python -m pytest tests/test_service.py -v
+    cd backend && python -m pytest tests/test_cases/service/test_service.py -v
 """
 
 from __future__ import annotations