fix(backend): ajoute l'en-tete Cross-Origin-Resource-Policy sur toutes les reponses

apps/backend/app/api/middleware.py

@@ -16,6 +16,9 @@ EN_TETES: Final[dict[str, str]] = {
     "X-Content-Type-Options": "nosniff",
     "X-Frame-Options": "DENY",
     "Referrer-Policy": "no-referrer",
+    # same-origin : le frontend ne consomme l'API qu'au travers d'un proxy same-origin
+    # (proxy.conf.json en dev, ingress /api en prod, cf. docs/architecture/20-backend.md).
+    "Cross-Origin-Resource-Policy": "same-origin",
 }
 
 PREFIXE_AUTHENTIFICATION: Final = "/auth"

apps/backend/tests/api/test_hardening.py

@@ -23,8 +23,9 @@ async def interroge(
         ("x-content-type-options", "nosniff"),
         ("x-frame-options", "DENY"),
         ("referrer-policy", "no-referrer"),
+        ("cross-origin-resource-policy", "same-origin"),
     ],
-    ids=["nosniff", "anti_iframe", "referrer"],
+    ids=["nosniff", "anti_iframe", "referrer", "corp"],
 )
 async def test_every_response_carries_the_security_headers(
     client: AsyncClient, entete: str, valeur: str