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/models/message.py

@@ -0,0 +1,33 @@
+"""消息数据模型"""
+
+from dataclasses import dataclass, field
+from datetime import datetime
+from typing import Dict, List, Literal, Optional, Any
+
+
+@dataclass
+class ToolCall:
+    """工具调用"""
+    id: str
+    name: str
+    arguments: Dict[str, Any]
+
+
+@dataclass
+class ToolResult:
+    """工具执行结果"""
+    tool_call_id: str
+    name: str
+    arguments: Dict[str, Any]
+    result: str
+    success: bool
+
+
+@dataclass
+class Message:
+    """消息"""
+    role: Literal["user", "assistant", "system"]
+    content: str
+    timestamp: datetime = field(default_factory=datetime.now)
+    tool_calls: Optional[List[ToolCall]] = None
+    tool_results: Optional[List[ToolResult]] = None