refactor(repo): consolidate openflare-server to root and move subprojects to internal/apps

- Merge all files inside openflare-server to the repository root directory.
- Relocate agent, relay, and flared subprojects from internal/ to internal/apps/.
- Combine docker-compose files and update build context paths to root.
- Update GitHub workflows and Dockerfiles to refer to new directories and package names.
- Rewrite Go package imports across all files.
- Resolve database renew test race condition and clean up docs.

internal/apps/openflare/flared/observability.go

@@ -0,0 +1,50 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package flared
+
+import (
+	"context"
+	"fmt"
+	"strings"
+	"time"
+
+	"github.com/Rain-kl/Wavelet/internal/apps/openflare/agent"
+	"github.com/Rain-kl/Wavelet/internal/db"
+	"go.uber.org/zap"
+)
+
+const flaredRuntimeUnhealthyEventType = "flared_runtime_unhealthy"
+
+func persistFlaredObservability(ctx context.Context, nodeID string, payload HeartbeatPayload, reportedAt time.Time) {
+	connected := make([]string, 0, len(payload.ConnectedRelays))
+	for _, relay := range payload.ConnectedRelays {
+		connected = append(connected, fmt.Sprintf("%s:%s", relay.RelayNodeID, relay.Status))
+	}
+	managedTypes := map[string]struct{}{
+		flaredRuntimeUnhealthyEventType: {},
+	}
+	var events []agent.NodeHealthEvent
+	if payload.TunnelStatus == "unhealthy" {
+		events = append(events, agent.NodeHealthEvent{
+			EventType:       flaredRuntimeUnhealthyEventType,
+			Severity:        "critical",
+			Message:         "openflared runtime is not healthy",
+			TriggeredAtUnix: reportedAt.Unix(),
+			Metadata: map[string]string{
+				"tunnel_status":    payload.TunnelStatus,
+				"client_version":   payload.ClientVersion,
+				"current_version":  payload.CurrentVersion,
+				"current_checksum": payload.CurrentChecksum,
+				"connected_relays": strings.Join(connected, ","),
+			},
+		})
+	}
+	conn := db.DB(ctx)
+	if conn == nil {
+		return
+	}
+	if err := agent.ReconcileScopedNodeHealthEvents(conn, nodeID, events, reportedAt, managedTypes); err != nil {
+		zap.L().Error("persist flared health events failed", zap.String("node_id", nodeID), zap.Error(err))
+	}
+}