refactor: restructure to core/ + ui/ with multi-threaded backend

ui/widgets/status_bar.py

@@ -0,0 +1,27 @@
+"""状态栏组件"""
+
+from textual.widgets import Static
+from textual.message import Message
+
+
+class StatusBar(Static):
+    """底部状态栏"""
+
+    class FocusChanged(Message):
+        """焦点变更事件"""
+        def __init__(self, focus_name: str) -> None:
+            self.focus_name = focus_name
+            super().__init__()
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+        self._shortcuts = "F1:帮助 F2:侧边栏 F3:工具详情 F4:查询 F5:清屏 F6:退出"
+        self._license_info = "本项目由jianf设计，以GPLv3形式开源"
+
+    def on_mount(self) -> None:
+        """组件挂载时"""
+        self._update_display()
+
+    def _update_display(self) -> None:
+        """更新显示"""
+        self.update(f"{self._license_info} | {self._shortcuts}")