refactor(edge): 抽取边缘运行时共享包并完成 Phase 3 重构

- 新增 internal/apps/edge/，三组件改为薄包装，删除 3000+ 行重复代码
- Agent 心跳周期下沉至 heartbeat/cycle.go
- 协议类型迁入 pkg/protocol/agent.go
- 补充设计文档与 changelog

internal/apps/edge/updater/restart_windows.go

@@ -0,0 +1,53 @@
+//go:build windows
+
+package updater
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+)
+
+func replaceAndRestart(execPath string, tmpPath string) error {
+	backupPath := execPath + ".bak"
+	scriptPath := execPath + ".update.cmd"
+	script := fmt.Sprintf(`@echo off
+setlocal
+:waitloop
+move /Y "%s" "%s" >nul 2>nul
+if errorlevel 1 (
+  ping 127.0.0.1 -n 2 >nul
+  goto waitloop
+)
+move /Y "%s" "%s" >nul 2>nul
+if errorlevel 1 exit /b 1
+start "" %s
+del /Q "%s" >nul 2>nul
+del /Q "%%~f0" >nul 2>nul
+`, execPath, backupPath, tmpPath, execPath, buildWindowsCommandLine(execPath, os.Args[1:]), backupPath)
+	if err := os.WriteFile(scriptPath, []byte(script), 0o700); err != nil {
+		os.Remove(tmpPath)
+		return fmt.Errorf("write restart script: %w", err)
+	}
+	cmd := exec.Command("cmd", "/C", "start", "", scriptPath)
+	if err := cmd.Start(); err != nil {
+		os.Remove(scriptPath)
+		os.Remove(tmpPath)
+		return fmt.Errorf("schedule restart: %w", err)
+	}
+	os.Exit(0)
+	return nil
+}
+
+func buildWindowsCommandLine(execPath string, args []string) string {
+	parts := []string{quoteWindowsArg(execPath)}
+	for _, arg := range args {
+		parts = append(parts, quoteWindowsArg(arg))
+	}
+	return strings.Join(parts, " ")
+}
+
+func quoteWindowsArg(value string) string {
+	return `"` + strings.ReplaceAll(value, `"`, `""`) + `"`
+}