feat: add auto-save debounce, note refetch on switch, todos feature with markdown

Features implemented:
- Auto-save with counter-based debounce in note editor
- Note refetches when switching between notes (note_id prop changes)
- Todos feature with full CRUD operations
- Markdown rendering in todo titles
- API endpoints for todos (create, list, toggle, delete)
- Todo panel in sidebar with sorting (incomplete first, newest first)
- Todo items use TodoItem component for clean separation

Technical changes:
- Added Todo struct and API endpoints in api package
- Added markdown dependency to web package
- Implemented TodoPanel component with TodoItem sub-component
- Added mut keywords to signal bindings for Dioxus 0.7
- Fixed closure capture issues with cloning todo objects

packages/api/src/lib.rs

@@ -15,6 +15,15 @@ pub struct Note {
     pub is_pinned: bool,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+pub struct Todo {
+    pub id: String,
+    pub title: String,
+    pub completed: bool,
+    pub created_at: DateTime<Utc>,
+    pub due_date: Option<DateTime<Utc>>,
+}
+
 impl Note {
     pub fn new(title: String, content: String, tags: Vec<String>) -> Self {
         let now = Utc::now();
@@ -30,7 +39,21 @@ impl Note {
     }
 }
 
+impl Todo {
+    pub fn new(title: String, due_date: Option<DateTime<Utc>>) -> Self {
+        let now = Utc::now();
+        Self {
+            id: uuid::Uuid::new_v4().to_string(),
+            title,
+            completed: false,
+            created_at: now,
+            due_date,
+        }
+    }
+}
+
 type NotesStore = Mutex<Vec<Note>>;
+type TodosStore = Mutex<Vec<Todo>>;
 
 static NOTES: LazyLock<NotesStore> = LazyLock::new(|| {
     Mutex::new(vec![
@@ -52,6 +75,14 @@ static NOTES: LazyLock<NotesStore> = LazyLock::new(|| {
     ])
 });
 
+static TODOS: LazyLock<TodosStore> = LazyLock::new(|| {
+    Mutex::new(vec![
+        Todo::new("Review project proposal".to_string(), Some(Utc::now() + chrono::Duration::days(2))),
+        Todo::new("Complete documentation".to_string(), Some(Utc::now() + chrono::Duration::days(5))),
+        Todo::new("Team meeting preparation".to_string(), Some(Utc::now() + chrono::Duration::days(1))),
+    ])
+});
+
 #[post("/api/notes")]
 pub async fn create_note(title: String, content: String, tags: Vec<String>) -> Result<String, ServerFnError> {
     let mut notes = NOTES.lock().map_err(|e| ServerFnError::new(e.to_string()))?;
@@ -118,3 +149,41 @@ pub async fn toggle_pin_note(id: String) -> Result<(), ServerFnError> {
 pub async fn echo(message: String) -> Result<String, ServerFnError> {
     Ok(format!("Echo: {}", message))
 }
+
+// Todo endpoints
+#[post("/api/todos")]
+pub async fn create_todo(title: String, due_date: Option<String>) -> Result<String, ServerFnError> {
+    let mut todos = TODOS.lock().map_err(|e| ServerFnError::new(e.to_string()))?;
+    let due_date_parsed = due_date.and_then(|d| chrono::DateTime::parse_from_rfc3339(&d).ok()).map(|d| d.with_timezone(&Utc));
+    let todo = Todo::new(title, due_date_parsed);
+    todos.push(todo.clone());
+    Ok(todo.id)
+}
+
+#[get("/api/todos")]
+pub async fn list_todos() -> Result<Vec<Todo>, ServerFnError> {
+    let todos = TODOS.lock().map_err(|e| ServerFnError::new(e.to_string()))?;
+    Ok(todos.clone())
+}
+
+#[post("/api/todos/:id/toggle")]
+pub async fn toggle_todo(id: String) -> Result<(), ServerFnError> {
+    let mut todos = TODOS.lock().map_err(|e| ServerFnError::new(e.to_string()))?;
+    if let Some(todo) = todos.iter_mut().find(|t| t.id == id) {
+        todo.completed = !todo.completed;
+        Ok(())
+    } else {
+        Err(ServerFnError::new("Todo not found".to_string()))
+    }
+}
+
+#[post("/api/todos/:id/delete")]
+pub async fn delete_todo(id: String) -> Result<(), ServerFnError> {
+    let mut todos = TODOS.lock().map_err(|e| ServerFnError::new(e.to_string()))?;
+    if todos.iter().any(|t| t.id == id) {
+        todos.retain(|t| t.id != id);
+        Ok(())
+    } else {
+        Err(ServerFnError::new("Todo not found".to_string()))
+    }
+}