fix(tests): isolate test DB and sync tier=pro in Pro user fixtures

tests/conftest.py

@@ -1,3 +1,14 @@
+import os
+import tempfile
+from pathlib import Path
+
+# Use a temporary on-disk SQLite database for the test session so that
+# both the sync and async engines used by the app point at the same isolated
+# schema.  This avoids relying on (or mutating) the developer's data/translate.db.
+_test_db_file = tempfile.NamedTemporaryFile(suffix=".db", delete=False)
+_test_db_file.close()
+os.environ["SQLITE_PATH"] = _test_db_file.name
+
 import pytest
 import pytest_asyncio
 from typing import AsyncGenerator
@@ -14,6 +25,11 @@ TEST_DATABASE_URL = "sqlite+aiosqlite:///:memory:"
 def initialize_test_database():
     Base.metadata.create_all(bind=sync_engine)
     yield
+    # Clean up the temporary test database after the session.
+    try:
+        Path(_test_db_file.name).unlink(missing_ok=True)
+    except Exception:
+        pass
 
 
 @pytest_asyncio.fixture