Refactor MongoClient import: standardize import statements across push_notifications, tenant, and verify_audit_chain modules

Web/push_notifications.py

@@ -6,13 +6,13 @@ Handles Web Push notifications for users via Service Workers
 import os
 import json
 import datetime
-from pymongo import MongoClient
 from bson import ObjectId
 import requests
 import hashlib
 import logging
 
 import settings as cfg
+from settings import MongoClient
 
 logger = logging.getLogger(__name__)
 

Web/tenant.py

@@ -146,11 +146,18 @@ class TenantContext:
                 self.config = get_tenant_config(potential_subdomain)
                 return self._get_db_name(potential_subdomain)
 
-        # Fallback to default tenant if no tenant identifier found
+        # Fallback to default tenant if no tenant identifier found.
+        # If no explicit 'default' tenant config exists, use configured MongoDB DB.
+        if 'default' in TENANT_REGISTRY:
             self.tenant_id = 'default'
             self.config = get_tenant_config('default')
             return self._get_db_name('default')
 
+        self.tenant_id = None
+        self.config = {}
+        self.db_name = cfg.MONGODB_DB
+        return self.db_name
+
     def _get_db_name(self, tenant_id):
         """
         Get MongoDB database name for tenant.
@@ -214,8 +221,8 @@ def get_tenant_db(mongo_client):
     ctx = get_tenant_context()
     if ctx:
         return ctx.get_database(mongo_client)
-    # Fallback to default database
-    return mongo_client['inventar_default']
+    # Fallback to configured default database
+    return mongo_client[cfg.MONGODB_DB]
 
 
 def register_tenant(tenant_id, config=None):

Web/verify_audit_chain.py

@@ -4,9 +4,8 @@
 import json
 import sys
 
-from pymongo import MongoClient
-
 import settings as cfg
+from settings import MongoClient
 import audit_log as al