reminders: add ListReminders IPC + /reminders web page

Store layer: ListReminders returns the n most recent reminders
(newest first). IPC: new MethodListReminders wired through server,
client, and lockedAPI. Web: /reminders page with table of created
time, fire time, status badge, and payload text; empty state with
prompt to ask maven for a reminder. Sidebar entry under Automation.

internal/store/reminders.go

@@ -115,6 +115,26 @@ func (s *Store) MarkReminder(ctx context.Context, id int64, status string) error
 	return err
 }
 
+// ListReminders returns the n most recent reminders, newest first.
+func (s *Store) ListReminders(ctx context.Context, n int) ([]Reminder, error) {
+	rows, err := s.db.QueryContext(ctx, `
+		SELECT id, created_ts, fire_ts, next_fire_ts, payload, status, cron
+		  FROM reminders ORDER BY created_ts DESC, id DESC LIMIT ?`, n)
+	if err != nil {
+		return nil, fmt.Errorf("list reminders: %w", err)
+	}
+	defer rows.Close()
+	var out []Reminder
+	for rows.Next() {
+		r, err := scanReminder(rows)
+		if err != nil {
+			return nil, err
+		}
+		out = append(out, r)
+	}
+	return out, rows.Err()
+}
+
 // RescheduleReminder computes the next fire time for a recurring reminder and
 // updates next_fire_ts. Returns ErrReminderState if the reminder is not
 // recurring or not pending. If no more valid fire times exist, marks it fired.