Fix VuMark duplicate keys test isolation in Flask tests

Use distinct keys ("v1", "v2", "v3") for VuMark database tests to avoid
conflicts with the TARGET_MANAGER singleton state from cloud database tests.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: adamtheturtle

tests/mock_vws/test_flask_app_usage.py

@@ -176,26 +176,26 @@ def test_duplicate_vumark_keys() -> None:
         keys, including VuMark databases.
         """
         database = VuMarkDatabase(
-            server_access_key="1",
-            server_secret_key="2",
-            database_name="3",
+            server_access_key="v1",
+            server_secret_key="v2",
+            database_name="v3",
         )
 
-        bad_server_access_key_db = VuMarkDatabase(server_access_key="1")
-        bad_server_secret_key_db = VuMarkDatabase(server_secret_key="2")
-        bad_database_name_db = VuMarkDatabase(database_name="3")
+        bad_server_access_key_db = VuMarkDatabase(server_access_key="v1")
+        bad_server_secret_key_db = VuMarkDatabase(server_secret_key="v2")
+        bad_database_name_db = VuMarkDatabase(database_name="v3")
 
         server_access_key_conflict_error = (
             "All server access keys must be unique. "
-            'There is already a database with the server access key "1".'
+            'There is already a database with the server access key "v1".'
         )
         server_secret_key_conflict_error = (
             "All server secret keys must be unique. "
-            'There is already a database with the server secret key "2".'
+            'There is already a database with the server secret key "v2".'
         )
         database_name_conflict_error = (
             "All names must be unique. "
-            'There is already a database with the name "3".'
+            'There is already a database with the name "v3".'
         )
 
         databases_url = _EXAMPLE_URL_FOR_TARGET_MANAGER + "/vumark_databases"