Fix dashboard database initialization using temp file instead of in-memory

src/py_dvt_ate/app/dashboard/app.py

@@ -109,8 +109,12 @@ def init_session_state() -> None:
         st.session_state.instruments = InstrumentFactory.create(config)
 
     if "repository" not in st.session_state:
-        # Create test repository (in-memory for dashboard demo)
-        st.session_state.repository = SQLiteRepository(":memory:")
+        # Create test repository (temporary file for dashboard demo)
+        import os
+        import tempfile
+        tmpdir = tempfile.gettempdir()
+        db_path = os.path.join(tmpdir, "py_dvt_ate_dashboard.db")
+        st.session_state.repository = SQLiteRepository(db_path)
 
     if "test_runner" not in st.session_state:
         st.session_state.test_runner = TestRunner(st.session_state.repository)