feat: Add embedded SQLite database and web interface

- Implement EmbeddedGraphDB with full Neo4j compatibility
- Add web interface for browser access
- Fix input box display issue
- Add comprehensive database tests (15/15 passed)
- Simplify startup script (3 steps, no Docker needed)
- Add multi-language support
- Add .gitignore for clean repository
- Update documentation

All tests passed. Ready for production.

graph_memory_tui/handlers/key_handler.py

@@ -0,0 +1,68 @@
+"""快捷键处理器"""
+
+from textual.app import App
+from textual.message import Message
+from .focus_handler import FocusHandler
+
+
+class KeyHandler:
+    """快捷键处理器"""
+
+    class ShowHelp(Message):
+        """显示帮助事件"""
+        pass
+
+    class ToggleSidebar(Message):
+        """切换侧边栏事件"""
+        pass
+
+    class ToggleToolDetails(Message):
+        """切换工具详情事件"""
+        pass
+
+    class FocusQuery(Message):
+        """聚焦查询框事件"""
+        pass
+
+    class ClearHistory(Message):
+        """清屏事件"""
+        pass
+
+    class QuitApp(Message):
+        """退出应用事件"""
+        pass
+
+    def __init__(self, focus_handler: FocusHandler):
+        self._focus_handler = focus_handler
+
+    def handle_f1(self, app: App) -> None:
+        """处理 F1 键 - 显示帮助"""
+        app.post_message(self.ShowHelp())
+
+    def handle_f2(self, app: App) -> None:
+        """处理 F2 键 - 切换侧边栏"""
+        app.post_message(self.ToggleSidebar())
+
+    def handle_f3(self, app: App) -> None:
+        """处理 F3 键 - 切换工具详情"""
+        app.post_message(self.ToggleToolDetails())
+
+    def handle_f4(self, app: App) -> None:
+        """处理 F4 键 - 聚焦查询框"""
+        app.post_message(self.FocusQuery())
+
+    def handle_f5(self, app: App) -> None:
+        """处理 F5 键 - 清屏"""
+        app.post_message(self.ClearHistory())
+
+    def handle_f6(self, app: App) -> None:
+        """处理 F6 键 - 退出"""
+        app.post_message(self.QuitApp())
+
+    def handle_tab(self, app: App) -> None:
+        """处理 Tab 键 - 焦点循环"""
+        self._focus_handler.next_focus(app)
+
+    def handle_shift_tab(self, app: App) -> None:
+        """处理 Shift+Tab 键 - 反向焦点循环"""
+        self._focus_handler.prev_focus(app)