fix: Move date selection and datetime conversion before ticker selection

src/pages/backtesting/backtesting_page.py

@@ -233,6 +233,18 @@ def backtesting_page():
     with left_col:
         st.subheader("Backtest Settings")
         
+        # Date range selection
+        col1, col2 = st.columns(2)
+        with col1:
+            start_date = st.date_input("Start Date", 
+                                     value=datetime.now() - timedelta(days=365))
+        with col2:
+            end_date = st.date_input("End Date")
+            
+        # Convert dates to datetime objects
+        start_datetime = datetime.combine(start_date, datetime.min.time())
+        end_datetime = datetime.combine(end_date, datetime.min.time())
+
         # Add radio button for test mode
         test_mode = st.radio("Testing Mode", ["Single Ticker", "Multiple Tickers", "All Available Tickers"])
         
@@ -286,18 +298,6 @@ def backtesting_page():
             progress_bar = st.progress(0)
             status_text = st.empty()
         
-        # Date range selection
-        col1, col2 = st.columns(2)
-        with col1:
-            start_date = st.date_input("Start Date", 
-                                     value=datetime.now() - timedelta(days=365))
-        with col2:
-            end_date = st.date_input("End Date")
-            
-        # Convert dates to datetime objects
-        start_datetime = datetime.combine(start_date, datetime.min.time())
-        end_datetime = datetime.combine(end_date, datetime.min.time())
-        
         # Indicator selection
         available_indicators = get_available_indicators()
         selected_indicators = st.multiselect(