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/services/config_service.py

@@ -0,0 +1,51 @@
+"""配置服务"""
+
+from pathlib import Path
+from typing import TYPE_CHECKING
+from ..models.config import AppConfig
+
+if TYPE_CHECKING:
+    from ..core.imports import GraphMemoryClient
+
+
+class ConfigService:
+    """配置服务"""
+
+    DEFAULT_CONFIG_FILE = Path.home() / ".graph_memory_tui" / "config.json"
+
+    def __init__(self, config_file: Path | None = None):
+        self._config_file = config_file or self.DEFAULT_CONFIG_FILE
+        self._config = self._load_config()
+
+    def _load_config(self) -> AppConfig:
+        """加载配置"""
+        # 优先从文件加载
+        if self._config_file.exists():
+            return AppConfig.from_file(self._config_file)
+
+        # 否则从环境变量加载
+        return AppConfig.from_env()
+
+    def get_config(self) -> AppConfig:
+        """获取当前配置"""
+        return self._config
+
+    def set_config(self, config: AppConfig) -> None:
+        """设置配置"""
+        self._config = config
+        self._save_config()
+
+    def _save_config(self) -> None:
+        """保存配置"""
+        self._config.save(self._config_file)
+
+    def apply_to_client(self, client: "GraphMemoryClient") -> None:
+        """应用配置到 API 客户端"""
+        # 更新客户端配置
+        client.api_key = self._config.api_key
+        client.base_url = self._config.base_url
+        client.model = self._config.model
+
+    def get_config_file(self) -> Path:
+        """获取配置文件路径"""
+        return self._config_file