feat: 完成模拟交易闭环、App 与 A 股行情接入

统一单入口 Go 工程与前端依赖目录，增加后台供应商配置、候选审核、计划预算、成交冲正、持仓复盘和站内通知。接入策略版本、Python 回测、可配置 A 股公开行情及 zap 文件轮转日志，补充迁移、契约与验证。

internal/research/engine.go

@@ -0,0 +1,46 @@
+// Package research executes the embedded Python research engine with bounded inputs.
+package research
+
+import (
+	"bytes"
+	"context"
+	_ "embed"
+	"encoding/json"
+	"errors"
+	"os"
+	"os/exec"
+	"time"
+)
+
+//go:embed backtest.py
+var script string
+
+type Engine struct{ executable string }
+
+func New(executable string) *Engine { return &Engine{executable} }
+func (e *Engine) Execute(ctx context.Context, input json.RawMessage) (json.RawMessage, error) {
+	ctx, cancel := context.WithTimeout(ctx, 20*time.Second)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, e.executable, "-I", "-c", script)
+	// No application credentials or Python startup configuration reach the child.
+	cmd.Env = []string{"PATH=" + os.Getenv("PATH"), "LANG=en_US.UTF-8"}
+	cmd.Stdin = bytes.NewReader(input)
+	var output boundedBuffer
+	cmd.Stdout = &output
+	if err := cmd.Run(); err != nil {
+		return nil, errors.New("Python research execution failed; check Python installation and input data")
+	}
+	if !json.Valid(output.Bytes()) {
+		return nil, errors.New("invalid research result")
+	}
+	return json.RawMessage(output.Bytes()), nil
+}
+
+type boundedBuffer struct{ bytes.Buffer }
+
+func (b *boundedBuffer) Write(p []byte) (int, error) {
+	if b.Len()+len(p) > 2<<20 {
+		return 0, errors.New("research output exceeds limit")
+	}
+	return b.Buffer.Write(p)
+}