feat(src/window/pomodoro): implement Pomodoro timer widget and integrate it into the panel

Add Pomodoro component with UI controls and state management,
modify Panel to instantiate and cache Pomodoro and TodoList widgets,
hook datetime button to toggle Pomodoro and handle right‑click on todo list,
extend destroy logic to cleanly close Pomodoro and Todo instances.

src/window/panel/main.py

@@ -1,5 +1,5 @@
 from fabric.system_tray.widgets import SystemTray
-from fabric.utils import logger
+from fabric.utils import Gdk, logger
 from fabric.widgets.box import Box
 from fabric.widgets.button import Button
 from fabric.widgets.centerbox import CenterBox
@@ -109,8 +109,16 @@ class Panel(Window):
             name="panel-button",
             child=DateTime(name="date-time", formatters=["%a %-d %b %I:%M %P"]),
         )
+        self.datetime_btn.add_events(
+            Gdk.EventMask.BUTTON_PRESS_MASK | Gdk.EventMask.BUTTON_RELEASE_MASK
+        )
         setup_cursor_hover(self.datetime_btn, "pointer")
 
+        self._pomodoro_instance = None
+        self._todo_instance = None
+        self.datetime_btn.connect("clicked", self.on_datetime_clicked)
+        self.datetime_btn.connect("button-press-event", self.on_datetime_right_click)
+
         self.custom_mods = CustomMods(parent_window=self)
         self.workspace_indicator = WorkspaceIndicator()
 
@@ -178,6 +186,36 @@ class Panel(Window):
     def on_notification_icon_clicked(self, *_):
         self.notification_center.toggle()
 
+    def on_datetime_clicked(self, *_):
+        self.pomodoro.toggle()
+
+    def on_datetime_right_click(self, widget, event):
+        logger.info(f"[Panel] Right click detected: button={event.button}")
+        if event.button == 3:  # Right click
+            self.todo_widget.toggle()
+            return True
+        return False
+
+    @property
+    def pomodoro(self):
+        if self._pomodoro_instance is None:
+            from window.panel.components.pomodoro import Pomodoro
+
+            self._pomodoro_instance = Pomodoro(
+                parent=self, pointing_to=self.datetime_btn
+            )
+        return self._pomodoro_instance
+
+    @property
+    def todo_widget(self):
+        if self._todo_instance is None:
+            from window.panel.components.todo import TodoListWidget
+
+            self._todo_instance = TodoListWidget(
+                parent=self, pointing_to=self.datetime_btn
+            )
+        return self._todo_instance
+
     @property
     def control_center(self):
         if self._control_center_instance is None:
@@ -351,9 +389,15 @@ class Panel(Window):
                 logger.error(f"An error occurred: {e}")
 
         # Destroy MouseCapture windows
-        for mc in [self.control_center, self.notification_center]:
+        for mc in [
+            self.control_center,
+            self.notification_center,
+            self._pomodoro_instance,
+            self._todo_instance,
+        ]:
             try:
-                mc.destroy()
+                if mc:
+                    mc.destroy()
             except Exception as e:
                 logger.error(f"An error occurred: {e}")