Collect start date and reminder state

Already fetch the start date and reminder state for issues immediately
and have them available in the struct Task.

src/task.rs

@@ -15,22 +15,28 @@ pub struct Task {
 
 #[derive(Debug, Clone)]
 pub enum State {
-    /// The task is open and pending completion.
-    ///
-    /// An optional due date may be present.
-    Open { due: Option<jiff::Zoned> },
+    /// The task is open but has no due date.
+    Open,
+
+    /// The task is scheduled and waiting for completion.
+    Scheduled(ScheduledInfo),
 
     /// The task has been completed at the specified time.
     Completed { date: jiff::Zoned },
 }
 
-impl State {
-    pub fn due_date_if_open(&self) -> Option<&jiff::Zoned> {
-        match self {
-            State::Open { due } => due.as_ref(),
-            _ => None,
-        }
-    }
+#[derive(Debug, Clone)]
+pub struct ScheduledInfo {
+    pub due_date: jiff::Zoned,
+    pub start_date: jiff::Zoned,
+    pub reminded: ReminderState,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum ReminderState {
+    NotReminded,
+    Reminded { date: jiff::Zoned },
+    RemindedUrgently { date: jiff::Zoned },
 }
 
 #[derive(Debug, Clone)]