feat(gateway): add WhatsApp Cloud adapter

surfsense_backend/app/gateway/whatsapp/credentials.py

@@ -0,0 +1,31 @@
+"""Credential helpers for WhatsApp gateway accounts."""
+
+from __future__ import annotations
+
+from typing import TypedDict
+
+from app.config import config
+
+
+class WhatsAppCredentials(TypedDict, total=False):
+    business_token: str
+    waba_id: str
+    phone_number_id: str
+    business_id: str
+    registration_pin: str
+    api_version: str
+
+
+def load_system_whatsapp_credentials() -> WhatsAppCredentials:
+    if not (
+        config.WHATSAPP_SHARED_BUSINESS_TOKEN
+        and config.WHATSAPP_SHARED_PHONE_NUMBER_ID
+    ):
+        raise RuntimeError("whatsapp_system_credentials_not_configured")
+
+    return {
+        "business_token": config.WHATSAPP_SHARED_BUSINESS_TOKEN,
+        "phone_number_id": config.WHATSAPP_SHARED_PHONE_NUMBER_ID,
+        "waba_id": config.WHATSAPP_SHARED_WABA_ID,
+        "api_version": config.WHATSAPP_GRAPH_API_VERSION,
+    }