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/app/config.py

@@ -0,0 +1,43 @@
+"""Application configuration via Pydantic Settings."""
+
+from pydantic_settings import BaseSettings, SettingsConfigDict
+
+
+class Settings(BaseSettings):
+    """Settings loaded from environment variables."""
+
+    model_config = SettingsConfigDict(env_file=".env", extra="ignore")
+
+    # Database
+    DATABASE_URL: str = "postgresql+asyncpg://hms:hms@localhost:5432/hms"
+
+    # Redis
+    REDIS_URL: str = "redis://localhost:6379/0"
+
+    # CORS
+    CORS_ORIGINS: str = "https://hms.media-on.de,http://localhost:3000"
+
+    # Rentman
+    RENTMAN_API_TOKEN: str = ""
+
+    # Auth
+    JWT_SECRET: str = "dev-secret-change-me"
+
+    # SMTP
+    SMTP_HOST: str = ""
+    SMTP_PORT: int = 587
+    SMTP_USER: str = ""
+    SMTP_PASSWORD: str = ""
+    SMTP_FROM: str = "info@hms-licht-ton.de"
+
+    # Admin
+    ADMIN_USERNAME: str = "admin"
+    ADMIN_PASSWORD: str = "change_me"
+
+    @property
+    def cors_origins_list(self) -> list[str]:
+        """Parse CORS_ORIGINS into a list."""
+        return [origin.strip() for origin in self.CORS_ORIGINS.split(",") if origin.strip()]
+
+
+settings = Settings()