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/focus_handler.py

@@ -0,0 +1,64 @@
+"""焦点管理器"""
+
+from textual.app import App
+
+
+class FocusHandler:
+    """焦点管理器"""
+
+    # 焦点循环顺序
+    FOCUS_RING = [
+        "input-textarea",      # 左侧输入框
+        "api-key-input",       # 右侧配置区 API Key
+        "model-input",         # 右侧配置区 Model
+        "base-url-input",      # 右侧配置区 Base URL
+        "cypher-textarea",     # 右侧 Cypher 查询框
+    ]
+
+    # 焦点名称映射
+    FOCUS_NAMES = {
+        "input-textarea": "Input",
+        "api-key-input": "Config-API",
+        "model-input": "Config-Model",
+        "base-url-input": "Config-URL",
+        "cypher-textarea": "Query",
+    }
+
+    def __init__(self):
+        self._current_index = 0
+
+    def next_focus(self, app: App) -> None:
+        """切换到下一个焦点"""
+        self._current_index = (self._current_index + 1) % len(self.FOCUS_RING)
+        widget_id = self.FOCUS_RING[self._current_index]
+        self._focus_widget(app, widget_id)
+
+    def prev_focus(self, app: App) -> None:
+        """切换到上一个焦点"""
+        self._current_index = (self._current_index - 1) % len(self.FOCUS_RING)
+        widget_id = self.FOCUS_RING[self._current_index]
+        self._focus_widget(app, widget_id)
+
+    def focus_input(self, app: App) -> None:
+        """聚焦到输入框"""
+        self._current_index = 0
+        self._focus_widget(app, self.FOCUS_RING[0])
+
+    def focus_query(self, app: App) -> None:
+        """聚焦到查询框"""
+        self._current_index = len(self.FOCUS_RING) - 1
+        self._focus_widget(app, self.FOCUS_RING[-1])
+
+    def get_current_focus_name(self) -> str:
+        """获取当前焦点名称"""
+        widget_id = self.FOCUS_RING[self._current_index]
+        return self.FOCUS_NAMES.get(widget_id, "Unknown")
+
+    def _focus_widget(self, app: App, widget_id: str) -> None:
+        """聚焦到指定组件"""
+        try:
+            widget = app.query_one(f"#{widget_id}")
+            widget.focus()
+        except Exception:
+            # 如果找不到组件，回退到输入框
+            self.focus_input(app)