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/.env.test

@@ -0,0 +1,19 @@
+# ROA2WEB Backend - TEST Environment Configuration
+# Used by start-test.sh for Oracle TEST server (LXC 10.0.20.121)
+
+# Oracle TEST Database (container db with service "roa")
+ORACLE_USER=CONTAFIN_ORACLE
+ORACLE_PASSWORD=ROMFASTSOFT
+ORACLE_DSN=localhost:1526/roa
+
+# Test credentials for pytest (user exists in Oracle TEST)
+TEST_ORACLE_USER=MARIUS M
+TEST_ORACLE_PASS=123
+
+# Test company - MARIUSM_AUTO schema (only schema with full data in TEST)
+# Other schemas (ACN, DANUBE, EMS) don't have required tables
+TEST_COMPANY_ID=110
+TEST_COMPANY_SCHEMA=MARIUSM_AUTO
+
+# Cache (separate from production)
+CACHE_SQLITE_PATH=./cache_data/roa2web_cache_test.db