feat: 重构前后端架构，添加Go后端和Python Agent服务

- 新增 Go 语言后端服务(server/)，包含用户认证、Agent管理、数据库连接等API
- 新增 Python Agent 服务(agent/)，实现Agent核心逻辑和工具集
- 前端从原生HTML迁移到Vue.js框架(web/src/)
- 添加 Docker Compose 支持(docker-compose.yml)
- 添加项目架构文档(docs/ARCHITECTURE.md)
- 添加环境变量示例(.env.example)和本地启动脚本(start-local.ps1)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

agent/app/agent/tools/impl/calculator.py

@@ -0,0 +1,91 @@
+"""
+计算器工具
+"""
+import ast
+import operator
+from typing import Any
+
+
+# 安全运算符
+SAFE_OPERATORS = {
+    ast.Add: operator.add,
+    ast.Sub: operator.sub,
+    ast.Mult: operator.mul,
+    ast.Div: operator.truediv,
+    ast.Pow: operator.pow,
+    ast.Mod: operator.mod,
+    ast.USub: operator.neg,
+}
+
+
+def safe_eval_expr(node):
+    """安全地求值表达式节点"""
+    if isinstance(node, ast.Num):
+        return node.n
+    elif isinstance(node, ast.BinOp):
+        left = safe_eval_expr(node.left)
+        right = safe_eval_expr(node.right)
+        op_type = type(node.op)
+        if op_type in SAFE_OPERATORS:
+            return SAFE_OPERATORS[op_type](left, right)
+        raise ValueError(f"Unsupported operator: {op_type}")
+    elif isinstance(node, ast.UnaryOp):
+        operand = safe_eval_expr(node.operand)
+        op_type = type(node.op)
+        if op_type in SAFE_OPERATORS:
+            return SAFE_OPERATORS[op_type](operand)
+        raise ValueError(f"Unsupported unary operator: {op_type}")
+    else:
+        raise ValueError(f"Unsupported expression: {ast.dump(node)}")
+
+
+def calculate(expression: str) -> dict:
+    """
+    执行数学计算
+
+    Args:
+        expression: 数学表达式，如 "2 + 2" 或 "sqrt(16)"
+
+    Returns:
+        计算结果
+    """
+    try:
+        # 预处理：处理常见数学函数
+        expression = expression.replace("sqrt", "**0.5")
+        expression = expression.replace("pi", "3.14159265359")
+        expression = expression.replace("e", "2.71828182846")
+
+        # 解析表达式
+        tree = ast.parse(expression, mode='eval')
+        result = safe_eval_expr(tree.body)
+
+        return {
+            "success": True,
+            "expression": expression,
+            "result": result,
+            "type": type(result).__name__
+        }
+
+    except Exception as e:
+        return {
+            "success": False,
+            "expression": expression,
+            "error": str(e)
+        }
+
+
+# 工具定义
+TOOL_DEFINITION = {
+    "name": "calculator",
+    "description": "Perform mathematical calculations. Supports basic arithmetic (+, -, *, /), powers (**), and functions (sqrt).",
+    "parameters": {
+        "type": "object",
+        "properties": {
+            "expression": {
+                "type": "string",
+                "description": "Mathematical expression to evaluate, e.g., '2 + 2' or 'sqrt(16) + 5'"
+            }
+        },
+        "required": ["expression"]
+    }
+}