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_test.go

@@ -0,0 +1,71 @@
+// Copyright 2026 Arctel.net
+// SPDX-License-Identifier: Apache-2.0
+
+package flared
+
+import (
+	"context"
+	"testing"
+
+	"github.com/Rain-kl/Wavelet/internal/apps/openflare/agent"
+	"github.com/Rain-kl/Wavelet/internal/apps/openflare/option"
+	"github.com/Rain-kl/Wavelet/internal/db"
+	"github.com/Rain-kl/Wavelet/internal/model"
+	"github.com/glebarez/sqlite"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"gorm.io/gorm"
+)
+
+func setupFlaredObservabilityTestDB(t *testing.T) func() {
+	t.Helper()
+
+	sqliteDB, err := gorm.Open(sqlite.Open(":memory:"), &gorm.Config{
+		DisableForeignKeyConstraintWhenMigrating: true,
+	})
+	require.NoError(t, err)
+	require.NoError(t, sqliteDB.AutoMigrate(
+		&model.OpenFlareNode{},
+		&model.OpenFlareHealthEvent{},
+	))
+
+	db.SetDB(sqliteDB)
+	option.ResetInitializationForTest()
+	agent.ResetAuthCacheForTest()
+
+	return func() {
+		db.SetDB(nil)
+		option.ResetInitializationForTest()
+		agent.ResetAuthCacheForTest()
+	}
+}
+
+func TestHeartbeatFlaredEmitsHealthEventOnUnhealthy(t *testing.T) {
+	cleanup := setupFlaredObservabilityTestDB(t)
+	defer cleanup()
+
+	ctx := context.Background()
+	node := &model.OpenFlareNode{
+		NodeID:      "node-flared-unhealthy",
+		Name:        "flared-unhealthy",
+		AccessToken: "tunnel-token-unhealthy",
+		Status:      "pending",
+		NodeType:    "tunnel_client",
+	}
+	require.NoError(t, db.DB(ctx).Create(node).Error)
+
+	_, err := Heartbeat(ctx, node, HeartbeatPayload{
+		ClientVersion:   "v0.2.0",
+		FrpVersion:      "0.61.0",
+		TunnelStatus:    "unhealthy",
+		CurrentVersion:  "v1",
+		CurrentChecksum: "checksum-1",
+	})
+	require.NoError(t, err)
+
+	events, err := model.ListOpenFlareHealthEvents(ctx, node.NodeID, false, 20)
+	require.NoError(t, err)
+	require.Len(t, events, 1)
+	assert.Equal(t, flaredRuntimeUnhealthyEventType, events[0].EventType)
+	assert.Equal(t, "active", events[0].Status)
+}