feat: add reminder scheduling and sound controls

src/reminder/ReminderCommandHandler.h

@@ -0,0 +1,20 @@
+#pragma once
+
+#include "ReminderTypes.h"
+
+#include <QString>
+
+class ReminderManager;
+
+struct ReminderCommandResult
+{
+    bool success = false;
+    QString message;
+    ReminderItem item;
+};
+
+class ReminderCommandHandler
+{
+public:
+    static ReminderCommandResult handle(const QString &text, ReminderManager &manager);
+};