Fix blocklist service injection and centralize session cookie name

backend/app/utils/constants.py

@@ -39,6 +39,9 @@ SESSION_TOKEN_BYTES: Final[int] = 32
 SESSION_TOKEN_SIGNATURE_SEPARATOR: Final[str] = "."
 """Separator used to append a signature to a signed session token."""
 
+SESSION_COOKIE_NAME: Final[str] = "bangui_session"
+"""Name of the session cookie used by the browser SPA."""
+
 # ---------------------------------------------------------------------------
 # Time-range presets (used by dashboard and history endpoints)
 # ---------------------------------------------------------------------------