fix(server): stop the background compaction before the database is closed

The compaction starts right away in NewServer and could still write to the SQLite files while a
test's temp dir was removed ("directory not empty" on the CI runner, TestWebhookTokenInURLOnlyAPIKey).
Server.Close stops it and waits for a running pass; tests call it before closing the store, and the
server calls it on shutdown before the deferred store.Close. v0.37.1.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/api/server_test.go

@@ -46,6 +46,7 @@ func setupTestServer(t *testing.T) (*Server, *storage.Store, string) {
 	}
 	hub := ws.NewHub()
 	srv := NewServer(cfg, store, hub, nil)
+	t.Cleanup(srv.Close)
 
 	token, err := auth.GenerateToken(cfg.JWTSecret, user.ID, user.Email, user.DisplayName, user.TokenVersion, testSession(t, store, user.ID))
 	if err != nil {
@@ -71,6 +72,7 @@ func TestFirstBootSetupAndInviteRegistrationAndNonNullSlices(t *testing.T) {
 		AllowRegistration: false,
 	}
 	srv := NewServer(cfg, store, ws.NewHub(), nil)
+	t.Cleanup(srv.Close)
 	router := srv.Router()
 
 	// 1. Fresh DB must report needsSetup = true
@@ -455,6 +457,7 @@ func TestLoginWithUsernameAndDemoMode(t *testing.T) {
 		DemoMode:     true,
 	}
 	srv := NewServer(cfg, store, ws.NewHub(), nil)
+	t.Cleanup(srv.Close)
 	router := srv.Router()
 
 	// 1. Check auth status reports demoMode: true
@@ -542,6 +545,7 @@ func TestSpaceMembersDirectInvitationAPI(t *testing.T) {
 		JWTSecret:    "test-secret",
 	}
 	srv := NewServer(cfg, store, ws.NewHub(), nil)
+	t.Cleanup(srv.Close)
 	router := srv.Router()
 
 	adminUser, err := store.GetUserByLogin("admin")
@@ -771,6 +775,7 @@ func TestWebhookTriageBadgeAndIngestion(t *testing.T) {
 		AllowRegistration: false,
 	}
 	srv := NewServer(cfg, store, ws.NewHub(), nil)
+	t.Cleanup(srv.Close)
 	router := srv.Router()
 
 	// 1. Setup user
@@ -864,6 +869,7 @@ func TestSSEGlobalEndpoint(t *testing.T) {
 		AllowRegistration: false,
 	}
 	srv := NewServer(cfg, store, hub, nil)
+	t.Cleanup(srv.Close)
 	router := srv.Router()
 
 	setupBody := []byte(`{
@@ -1345,6 +1351,7 @@ func TestFirstBootSetupWithSampleData(t *testing.T) {
 	}
 	defer store.Close()
 	srv := NewServer(&config.Config{Port: "8080", DatabasePath: dbPath, JWTSecret: "test-jwt-secret-key"}, store, ws.NewHub(), nil)
+	t.Cleanup(srv.Close)
 
 	// Too short passwords are refused (FLAW-09)
 	short := httptest.NewRequest(http.MethodPost, "/api/v1/auth/setup", strings.NewReader(`{"email":"me@example.com","password":"secret"}`))