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/agent/observability/collector.go

@@ -1,21 +1,18 @@
 package observability
 
 import (
-	"bufio"
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
 	"os"
-	"path/filepath"
 	"runtime"
-	"strconv"
 	"strings"
-	"syscall"
 	"time"
 
 	"github.com/Rain-kl/Wavelet/internal/apps/agent/config"
 	"github.com/Rain-kl/Wavelet/internal/apps/agent/protocol"
 	"github.com/Rain-kl/Wavelet/internal/apps/agent/state"
+	edgeobs "github.com/Rain-kl/Wavelet/internal/apps/edge/observability"
 )
 
 func BuildProfile(cfg *config.Config, stateStore *state.Store) *protocol.NodeSystemProfile {
@@ -47,22 +44,22 @@ func BuildSnapshot(cfg *config.Config, stateStore *state.Store) *protocol.NodeMe
 		CapturedAtUnix: now.Unix(),
 	}
 
-	memTotal, memUsed := readMemInfo()
+	memTotal, memUsed := edgeobs.ReadMemInfo()
 	metric.MemoryTotalBytes = memTotal
 	metric.MemoryUsedBytes = memUsed
 
-	storageTotal, storageUsed := statFilesystem(cfg.DataDir)
+	storageTotal, storageUsed := edgeobs.StatFilesystem(cfg.DataDir)
 	metric.StorageTotalBytes = storageTotal
 	metric.StorageUsedBytes = storageUsed
 
-	metric.NetworkRxBytes, metric.NetworkTxBytes = readLinuxNetworkTotals()
-	metric.DiskReadBytes, metric.DiskWriteBytes = readLinuxDiskTotals()
+	metric.NetworkRxBytes, metric.NetworkTxBytes = edgeobs.ReadLinuxNetworkTotals()
+	metric.DiskReadBytes, metric.DiskWriteBytes = edgeobs.ReadLinuxDiskTotals()
 
 	if stateStore == nil {
 		return metric
 	}
 
-	totalCPU, idleCPU := readLinuxCPUStat()
+	totalCPU, idleCPU := edgeobs.ReadLinuxCPUStat()
 	snapshot, err := stateStore.Load()
 	if err != nil {
 		return metric
@@ -121,12 +118,12 @@ func BuildHealthEvents(snapshot *state.Snapshot) []protocol.NodeHealthEvent {
 
 func collectProfile(cfg *config.Config) *protocol.NodeSystemProfile {
 	hostname, _ := os.Hostname()
-	osName, osVersion := readLinuxOSRelease()
-	kernelVersion := readFirstLine("/proc/sys/kernel/osrelease")
-	cpuModel := readLinuxCPUModel()
-	totalMemory, _ := readMemInfo()
-	totalDisk, _ := statFilesystem(cfg.DataDir)
-	uptimeSeconds := readLinuxUptimeSeconds()
+	osName, osVersion := edgeobs.ReadLinuxOSRelease()
+	kernelVersion := edgeobs.ReadFirstLine("/proc/sys/kernel/osrelease")
+	cpuModel := edgeobs.ReadLinuxCPUModel()
+	totalMemory, _ := edgeobs.ReadMemInfo()
+	totalDisk, _ := edgeobs.StatFilesystem(cfg.DataDir)
+	uptimeSeconds := edgeobs.ReadLinuxUptimeSeconds()
 
 	return &protocol.NodeSystemProfile{
 		Hostname:         strings.TrimSpace(hostname),
@@ -150,255 +147,4 @@ func fingerprintProfile(profile *protocol.NodeSystemProfile) string {
 	}
 	sum := sha256.Sum256(raw)
 	return hex.EncodeToString(sum[:])
-}
-
-func readLinuxOSRelease() (string, string) {
-	file, err := os.Open("/etc/os-release")
-	if err != nil {
-		return runtime.GOOS, ""
-	}
-	defer file.Close()
-
-	values := make(map[string]string)
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := strings.TrimSpace(scanner.Text())
-		if line == "" || strings.HasPrefix(line, "#") {
-			continue
-		}
-		key, value, ok := strings.Cut(line, "=")
-		if !ok {
-			continue
-		}
-		values[key] = strings.Trim(value, `"`)
-	}
-	if pretty := strings.TrimSpace(values["PRETTY_NAME"]); pretty != "" {
-		return pretty, strings.TrimSpace(values["VERSION_ID"])
-	}
-	name := strings.TrimSpace(values["NAME"])
-	if name == "" {
-		name = runtime.GOOS
-	}
-	return name, strings.TrimSpace(values["VERSION_ID"])
-}
-
-func readLinuxCPUModel() string {
-	file, err := os.Open("/proc/cpuinfo")
-	if err != nil {
-		return ""
-	}
-	defer file.Close()
-
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := scanner.Text()
-		if strings.HasPrefix(strings.ToLower(line), "model name") {
-			_, value, ok := strings.Cut(line, ":")
-			if ok {
-				return strings.TrimSpace(value)
-			}
-		}
-	}
-	return ""
-}
-
-func readMemInfo() (int64, int64) {
-	file, err := os.Open("/proc/meminfo")
-	if err != nil {
-		return 0, 0
-	}
-	defer file.Close()
-
-	var memTotalKB int64
-	var memAvailableKB int64
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := scanner.Text()
-		switch {
-		case strings.HasPrefix(line, "MemTotal:"):
-			memTotalKB = parseMemInfoValue(line)
-		case strings.HasPrefix(line, "MemAvailable:"):
-			memAvailableKB = parseMemInfoValue(line)
-		}
-	}
-
-	total := memTotalKB * 1024
-	if total == 0 {
-		return 0, 0
-	}
-	used := total - (memAvailableKB * 1024)
-	if used < 0 {
-		used = 0
-	}
-	return total, used
-}
-
-func parseMemInfoValue(line string) int64 {
-	fields := strings.Fields(line)
-	if len(fields) < 2 {
-		return 0
-	}
-	value, err := strconv.ParseInt(fields[1], 10, 64)
-	if err != nil {
-		return 0
-	}
-	return value
-}
-
-func readLinuxUptimeSeconds() int64 {
-	content, err := os.ReadFile("/proc/uptime")
-	if err != nil {
-		return 0
-	}
-	fields := strings.Fields(string(content))
-	if len(fields) == 0 {
-		return 0
-	}
-	value, err := strconv.ParseFloat(fields[0], 64)
-	if err != nil {
-		return 0
-	}
-	return int64(value)
-}
-
-func readLinuxCPUStat() (uint64, uint64) {
-	content, err := os.ReadFile("/proc/stat")
-	if err != nil {
-		return 0, 0
-	}
-	lines := strings.Split(string(content), "\n")
-	for _, line := range lines {
-		if !strings.HasPrefix(line, "cpu ") {
-			continue
-		}
-		fields := strings.Fields(line)
-		if len(fields) < 5 {
-			return 0, 0
-		}
-		var total uint64
-		for i := 1; i < len(fields); i++ {
-			value, err := strconv.ParseUint(fields[i], 10, 64)
-			if err != nil {
-				return 0, 0
-			}
-			total += value
-			if i == 4 {
-				// idle
-			}
-		}
-		idle, err := strconv.ParseUint(fields[4], 10, 64)
-		if err != nil {
-			return 0, 0
-		}
-		return total, idle
-	}
-	return 0, 0
-}
-
-func readLinuxNetworkTotals() (int64, int64) {
-	file, err := os.Open("/proc/net/dev")
-	if err != nil {
-		return 0, 0
-	}
-	defer file.Close()
-
-	var rx int64
-	var tx int64
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		line := strings.TrimSpace(scanner.Text())
-		if !strings.Contains(line, ":") {
-			continue
-		}
-		name, data, ok := strings.Cut(line, ":")
-		if !ok {
-			continue
-		}
-		if strings.TrimSpace(name) == "lo" {
-			continue
-		}
-		fields := strings.Fields(data)
-		if len(fields) < 16 {
-			continue
-		}
-		rxValue, err := strconv.ParseInt(fields[0], 10, 64)
-		if err == nil {
-			rx += rxValue
-		}
-		txValue, err := strconv.ParseInt(fields[8], 10, 64)
-		if err == nil {
-			tx += txValue
-		}
-	}
-	return rx, tx
-}
-
-func readLinuxDiskTotals() (int64, int64) {
-	file, err := os.Open("/proc/diskstats")
-	if err != nil {
-		return 0, 0
-	}
-	defer file.Close()
-
-	var readBytes int64
-	var writeBytes int64
-	scanner := bufio.NewScanner(file)
-	for scanner.Scan() {
-		fields := strings.Fields(scanner.Text())
-		if len(fields) < 14 {
-			continue
-		}
-		device := fields[2]
-		if shouldSkipDiskDevice(device) {
-			continue
-		}
-		readSectors, err := strconv.ParseInt(fields[5], 10, 64)
-		if err == nil {
-			readBytes += readSectors * 512
-		}
-		writeSectors, err := strconv.ParseInt(fields[9], 10, 64)
-		if err == nil {
-			writeBytes += writeSectors * 512
-		}
-	}
-	return readBytes, writeBytes
-}
-
-func shouldSkipDiskDevice(device string) bool {
-	switch {
-	case device == "":
-		return true
-	case strings.HasPrefix(device, "loop"),
-		strings.HasPrefix(device, "ram"),
-		strings.HasPrefix(device, "dm-"):
-		return true
-	default:
-		return false
-	}
-}
-
-func statFilesystem(path string) (int64, int64) {
-	if strings.TrimSpace(path) == "" {
-		path = string(os.PathSeparator)
-	}
-	absPath := filepath.Clean(path)
-	var stat syscall.Statfs_t
-	if err := syscall.Statfs(absPath, &stat); err != nil {
-		return 0, 0
-	}
-	total := int64(stat.Blocks) * int64(stat.Bsize)
-	free := int64(stat.Bavail) * int64(stat.Bsize)
-	used := total - free
-	if used < 0 {
-		used = 0
-	}
-	return total, used
-}
-
-func readFirstLine(path string) string {
-	content, err := os.ReadFile(path)
-	if err != nil {
-		return ""
-	}
-	return strings.TrimSpace(string(content))
-}
+}