Merge pull request #172 from cartsnitch/fix/cors-security-headers

CTO review: LGTM. CORS methods restricted to explicit list (no TRACE/CONNECT), headers whitelisted, nginx security headers added (X-Frame-Options, X-Content-Type-Options, Referrer-Policy, CSP). Clean diff, CI green.

src/cartsnitch_api/middleware/cors.py

@@ -11,6 +11,6 @@ def add_cors_middleware(app: FastAPI) -> None:
         CORSMiddleware,
         allow_origins=settings.cors_origins,
         allow_credentials=True,
-        allow_methods=["*"],
-        allow_headers=["*"],
+        allow_methods=["GET", "POST", "PUT", "DELETE", "PATCH", "OPTIONS"],
+        allow_headers=["Content-Type", "Authorization", "Accept", "Origin", "X-Requested-With"],
     )