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/flared/heartbeat/service.go

@@ -3,23 +3,16 @@ package heartbeat
 import (
 	"context"
 	"log/slog"
-	"net"
-	"time"
 
+	edgeheartbeat "github.com/Rain-kl/Wavelet/internal/apps/edge/heartbeat"
+	"github.com/Rain-kl/Wavelet/internal/apps/edge/nodeip"
 	"github.com/Rain-kl/Wavelet/internal/apps/flared/config"
 	"github.com/Rain-kl/Wavelet/internal/apps/flared/frpc"
 	"github.com/Rain-kl/Wavelet/internal/apps/flared/httpclient"
 	"github.com/Rain-kl/Wavelet/internal/apps/flared/updater"
-	"github.com/Rain-kl/Wavelet/pkg/geoip"
-	"github.com/Rain-kl/Wavelet/pkg/geoip/iputil"
 	service "github.com/Rain-kl/Wavelet/pkg/protocol"
 )
 
-var (
-	lookupOutboundIP = geoip.GetOutboundIP
-	lookupLocalIP    = detectLocalNodeIP
-)
-
 type Service struct {
 	client      *httpclient.Client
 	frpcManager *frpc.Manager
@@ -37,32 +30,17 @@ func New(client *httpclient.Client, manager *frpc.Manager, cfg *config.Config) *
 }
 
 func (s *Service) Run(ctx context.Context) {
-	ticker := time.NewTicker(s.config.HeartbeatInterval.Duration())
-	defer ticker.Stop()
-
-	// initial heartbeat
-	s.doHeartbeat(ctx)
-
-	for {
-		select {
-		case <-ctx.Done():
-			return
-		case <-ticker.C:
-			s.doHeartbeat(ctx)
-		}
-	}
+	edgeheartbeat.RunLoop(ctx, s.config.HeartbeatInterval.Duration(), s.doHeartbeat)
 }
 
 func (s *Service) doHeartbeat(ctx context.Context) {
 	slog.Debug("sending flared heartbeat")
 
-	ip := detectNodeIP()
-
 	payload := service.FlaredHeartbeatPayload{
 		ClientVersion:   config.Version,
 		FrpVersion:      s.frpcManager.GetVersion(),
-		IP:              ip,
-		TunnelStatus:    "running", // TODO implement proper status tracking
+		IP:              nodeip.Detect(),
+		TunnelStatus:    "running",
 		ConnectedRelays: s.frpcManager.GetConnectedRelays(),
 		CurrentVersion:  s.frpcManager.GetCurrentConfigVersion(),
 		CurrentChecksum: s.frpcManager.GetCurrentConfigChecksum(),
@@ -76,84 +54,19 @@ func (s *Service) doHeartbeat(ctx context.Context) {
 	slog.Debug("flared heartbeat succeeded")
 
 	if resp != nil && resp.TunnelSettings != nil {
-		s.tryAutoUpdate(ctx, resp.TunnelSettings)
+		edgeheartbeat.TryAutoUpdate(ctx, s.updater, tunnelSettingsToAutoUpdate(resp.TunnelSettings), "flared")
 	}
 }
 
-func (s *Service) tryAutoUpdate(ctx context.Context, settings *service.RelaySettings) {
-	if settings == nil || s.updater == nil {
-		return
+func tunnelSettingsToAutoUpdate(settings *service.RelaySettings) *edgeheartbeat.AutoUpdateSettings {
+	if settings == nil {
+		return nil
 	}
-	force := settings.UpdateNow
-	shouldCheck := settings.AutoUpdate || force
-	if !shouldCheck || settings.UpdateRepo == "" {
-		return
+	return &edgeheartbeat.AutoUpdateSettings{
+		AutoUpdate:    settings.AutoUpdate,
+		UpdateNow:     settings.UpdateNow,
+		UpdateRepo:    settings.UpdateRepo,
+		UpdateChannel: settings.UpdateChannel,
+		UpdateTag:     settings.UpdateTag,
 	}
-	channel := "stable"
-	if force && settings.UpdateChannel != "" {
-		channel = settings.UpdateChannel
-	}
-	slog.Info("checking for client updates", "repo", settings.UpdateRepo, "channel", channel, "force", force)
-	err := s.updater.CheckAndUpdate(ctx, settings.UpdateRepo, updater.UpdateOptions{
-		Channel: channel,
-		TagName: settings.UpdateTag,
-		Force:   force,
-	})
-	if err != nil {
-		slog.Error("client update check failed", "error", err)
-	}
-}
-
-func detectNodeIP() string {
-	if ip := detectOutboundNodeIP(); ip != "" {
-		return ip
-	}
-	return lookupLocalIP()
-}
-
-func detectOutboundNodeIP() string {
-	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
-	defer cancel()
-	ip, err := lookupOutboundIP(ctx)
-	if err != nil || ip == nil {
-		return ""
-	}
-	return ip.String()
-}
-
-func detectLocalNodeIP() string {
-	interfaces, err := net.Interfaces()
-	if err != nil {
-		return ""
-	}
-	bestIP := ""
-	bestPriority := -1
-	for _, iface := range interfaces {
-		if iface.Flags&net.FlagUp == 0 || iface.Flags&net.FlagLoopback != 0 {
-			continue
-		}
-		addrs, err := iface.Addrs()
-		if err != nil {
-			continue
-		}
-		for _, addr := range addrs {
-			ipNet, ok := addr.(*net.IPNet)
-			if !ok || ipNet.IP == nil || ipNet.IP.IsLoopback() {
-				continue
-			}
-			ipv4 := ipNet.IP.To4()
-			if ipv4 == nil {
-				continue
-			}
-			priority := iputil.Score(ipv4)
-			if priority > bestPriority {
-				bestIP = ipv4.String()
-				bestPriority = priority
-			}
-			if bestPriority == 2 {
-				return bestIP
-			}
-		}
-	}
-	return bestIP
-}
+}