feat: add todo management feature; implement todo content tracking and display in the UI

src/app/state/misc.rs

@@ -278,6 +278,7 @@ pub struct MiscState {
     pub editor: Option<super::super::mode::editor::EditorState>,
     pub api_connected: bool,
     pub tick_count: u64,
+    pub todo_content: String,
 }
 
 impl MiscState {
@@ -294,6 +295,7 @@ impl MiscState {
             editor: None,
             api_connected: false,
             tick_count: 0,
+            todo_content: String::new(),
         }
     }