feat: T03 backend core – FastAPI + DB models + Equipment API + Redis cache + health + tests

- FastAPI app with CORS, lifespan handlers
- Pydantic Settings config (DB, Redis, CORS, SMTP, JWT, Rentman)
- SQLAlchemy async engine + session (DeclarativeBase)
- 6 DB models: EquipmentCache, RentalRequest, RentalRequestItem, Contact, AdminUser, SyncLog
- Pydantic schemas: EquipmentItem, EquipmentDetail, PaginatedEquipment, ContactCreate, ContactResponse
- Redis cache helper: set/get/delete_pattern, rate limiting, equipment key builders
- Equipment router: list (search/category/sort/pagination), detail, categories – all cached
- Contact router: POST with Pydantic validation + rate limiting (5/min)
- Health router: GET /api/health with DB + Redis status
- 28 pytest tests (all pass, 90% coverage)
- Dockerfile, requirements.txt, pytest.ini, test_report.md

backend/requirements.txt

@@ -0,0 +1,15 @@
+fastapi>=0.111.0
+uvicorn[standard]>=0.30.0
+sqlalchemy[asyncio]>=2.0.0
+asyncpg>=0.29.0
+aiosqlite>=0.20.0
+pydantic>=2.0.0
+pydantic-settings>=2.0.0
+redis[hiredis]>=5.0.0
+python-multipart>=0.0.9
+httpx>=0.27.0
+pytest>=8.0.0
+pytest-asyncio>=0.23.0
+pytest-cov>=5.0.0
+fakeredis>=2.21.0
+apscheduler>=3.10.0