add a shit ton of feature for the custom srs

lib/src/screens/add_card_screen.dart

@@ -18,6 +18,7 @@ class _AddCardScreenState extends State<AddCardScreen> {
   final _kanjiController = TextEditingController();
   final _kanaKit = const KanaKit();
   final _deckRepository = CustomDeckRepository();
+  bool _useInterval = false;
 
   @override
   void initState() {
@@ -53,6 +54,8 @@ class _AddCardScreenState extends State<AddCardScreen> {
         characters: _japaneseController.text,
         meaning: _englishController.text,
         kanji: _kanjiController.text.isNotEmpty ? _kanjiController.text : null,
+        useInterval: _useInterval,
+        nextReview: _useInterval ? DateTime.now() : null,
       );
       _deckRepository.addCard(newItem);
       Navigator.of(context).pop();
@@ -106,6 +109,16 @@ class _AddCardScreenState extends State<AddCardScreen> {
                   return null;
                 },
               ),
+              const SizedBox(height: 16),
+              SwitchListTile(
+                title: const Text('Use Interval-based SRS'),
+                value: _useInterval,
+                onChanged: (value) {
+                  setState(() {
+                    _useInterval = value;
+                  });
+                },
+              ),
               const SizedBox(height: 32),
               ElevatedButton(
                 onPressed: _saveCard,