refactor(edge): Server 协议统一与 wsclient 收敛（Phase 3 Batch 3）

- openflare/agent/relay/flared 协议类型改为 pkg/protocol 别名，删除重复 struct
- 新增 edge/wsclient Preset 表，三组件 wsclient 改为薄包装
- 更新设计文档、计划与 changelog

internal/apps/openflare/agent/observability.go

@@ -29,82 +29,6 @@ const (
 	accessLogPathMaxLength       = 100
 )
 
-// NodeSystemProfile is the agent-reported system profile.
-type NodeSystemProfile struct {
-	Hostname         string `json:"hostname"`
-	OSName           string `json:"os_name"`
-	OSVersion        string `json:"os_version"`
-	KernelVersion    string `json:"kernel_version"`
-	Architecture     string `json:"architecture"`
-	CPUModel         string `json:"cpu_model"`
-	CPUCores         int    `json:"cpu_cores"`
-	TotalMemoryBytes int64  `json:"total_memory_bytes"`
-	TotalDiskBytes   int64  `json:"total_disk_bytes"`
-	UptimeSeconds    int64  `json:"uptime_seconds"`
-	ReportedAtUnix   int64  `json:"reported_at_unix"`
-}
-
-// NodeMetricSnapshot is the agent-reported capacity snapshot.
-type NodeMetricSnapshot struct {
-	CapturedAtUnix    int64   `json:"captured_at_unix"`
-	CPUUsagePercent   float64 `json:"cpu_usage_percent"`
-	MemoryUsedBytes   int64   `json:"memory_used_bytes"`
-	MemoryTotalBytes  int64   `json:"memory_total_bytes"`
-	StorageUsedBytes  int64   `json:"storage_used_bytes"`
-	StorageTotalBytes int64   `json:"storage_total_bytes"`
-	DiskReadBytes     int64   `json:"disk_read_bytes"`
-	DiskWriteBytes    int64   `json:"disk_write_bytes"`
-	NetworkRxBytes    int64   `json:"network_rx_bytes"`
-	NetworkTxBytes    int64   `json:"network_tx_bytes"`
-}
-
-// NodeOpenrestyObservation is the agent-reported openresty network observation.
-type NodeOpenrestyObservation struct {
-	CapturedAtUnix       int64 `json:"captured_at_unix"`
-	OpenrestyRxBytes     int64 `json:"openresty_rx_bytes"`
-	OpenrestyTxBytes     int64 `json:"openresty_tx_bytes"`
-	OpenrestyConnections int64 `json:"openresty_connections"`
-}
-
-// NodeTrafficReport is the agent-reported traffic window.
-type NodeTrafficReport struct {
-	WindowStartedAtUnix int64            `json:"window_started_at_unix"`
-	WindowEndedAtUnix   int64            `json:"window_ended_at_unix"`
-	RequestCount        int64            `json:"request_count"`
-	ErrorCount          int64            `json:"error_count"`
-	UniqueVisitorCount  int64            `json:"unique_visitor_count"`
-	StatusCodes         map[string]int64 `json:"status_codes"`
-	TopDomains          map[string]int64 `json:"top_domains"`
-	SourceCountries     map[string]int64 `json:"source_countries"`
-}
-
-// NodeAccessLog is a single access log row from the agent.
-type NodeAccessLog struct {
-	LoggedAtUnix int64  `json:"logged_at_unix"`
-	RemoteAddr   string `json:"remote_addr"`
-	Host         string `json:"host"`
-	Path         string `json:"path"`
-	StatusCode   int    `json:"status_code"`
-}
-
-// BufferedObservabilityRecord is a buffered observability window from the agent.
-type BufferedObservabilityRecord struct {
-	WindowStartedAtUnix  int64                     `json:"window_started_at_unix"`
-	Snapshot             *NodeMetricSnapshot       `json:"snapshot,omitempty"`
-	OpenrestyObservation *NodeOpenrestyObservation `json:"openresty_observation,omitempty"`
-	TrafficReport        *NodeTrafficReport        `json:"traffic_report,omitempty"`
-	AccessLogs           []NodeAccessLog           `json:"access_logs,omitempty"`
-}
-
-// NodeHealthEvent is an agent-reported health event.
-type NodeHealthEvent struct {
-	EventType       string            `json:"event_type"`
-	Severity        string            `json:"severity"`
-	Message         string            `json:"message"`
-	TriggeredAtUnix int64             `json:"triggered_at_unix"`
-	Metadata        map[string]string `json:"metadata"`
-}
-
 // PersistHeartbeatObservability stores profile, snapshots, traffic, access logs, and health events.
 func PersistHeartbeatObservability(ctx context.Context, nodeID string, payload NodePayload, reportedAt time.Time) {
 	if strings.TrimSpace(nodeID) == "" {