feat: Add backend tests with full cache initialization

- Add .env.test with test credentials and company config
- Add pytest fixtures for cache initialization (temp SQLite)
- Add test_api_real.py (18 tests) - API endpoint tests
- Add test_cache_real.py (8 tests) - Cache system tests
- Add test_services_real.py (9 tests) - Service layer tests
- Use company 110 (MARIUSM_AUTO) - only schema with full data in TEST

All 35 backend tests pass.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

reports-app/backend/tests/pytest.ini

@@ -0,0 +1,20 @@
+[pytest]
+testpaths = .
+python_files = test_*.py
+python_classes = Test*
+python_functions = test_*
+asyncio_mode = auto
+asyncio_default_fixture_loop_scope = session
+
+markers =
+    oracle: Tests that require Oracle database connection
+    slow: Tests that take longer than 5 seconds
+    cache: Tests for cache system
+
+filterwarnings =
+    ignore::DeprecationWarning
+    ignore::PendingDeprecationWarning
+
+# Default: run all tests
+# Skip slow: pytest -m "not slow"
+# Only Oracle: pytest -m oracle