refactor(zone): remove legacy route domain storage

第二阶段清理：删除 of_managed_domains 与 of_proxy_routes 冗余域名/证书列，
移除 ManagedDomain 模型与 API、路由侧 legacy 字段维护，以及前端 WebsiteService。
ImportLegacy 在旧列/旧表缺失时跳过对应源，保持幂等。

internal/apps/openflare/config_version/certificate_snapshot_test.go

@@ -75,7 +75,7 @@ func TestBuildSnapshotReadsZoneDomainCertificates(t *testing.T) {
 	second, err := oftls.CreateCertificate(ctx, oftls.CertificateInput{Name: "second", CertPEM: secondCertPEM, KeyPEM: secondKeyPEM})
 	require.NoError(t, err)
 
-	route := &model.ProxyRoute{SiteName: "tls-site", Domain: "legacy.invalid", OriginURL: "http://origin:8080", Upstreams: `["http://origin:8080"]`, Enabled: true, EnableHTTPS: true}
+	route := &model.ProxyRoute{SiteName: "tls-site", OriginURL: "http://origin:8080", Upstreams: `["http://origin:8080"]`, Enabled: true, EnableHTTPS: true}
 	require.NoError(t, model.CreateProxyRouteRecord(ctx, route))
 	zone := &model.Zone{Domain: "example.com"}
 	require.NoError(t, db.DB(ctx).Create(zone).Error)

internal/apps/openflare/config_version/logics_test.go

@@ -96,8 +96,6 @@ func TestPublishConfigVersionCreatesVersion(t *testing.T) {
 
 	route := &model.ProxyRoute{
 		SiteName:  "publish-site",
-		Domain:    "publish.example.com",
-		Domains:   `["publish.example.com"]`,
 		OriginURL: "http://origin.publish.example.com:8080",
 		Upstreams: `["http://origin.publish.example.com:8080"]`,
 		Enabled:   true,
@@ -142,8 +140,6 @@ func TestBuildSnapshotWAFDocumentUsesNormalizedSiteNames(t *testing.T) {
 
 	route := &model.ProxyRoute{
 		SiteName:  "example.com",
-		Domain:    "Example.COM",
-		Domains:   `["example.com","www.example.com"]`,
 		OriginURL: "http://origin.example.com:8080",
 		Upstreams: `["http://origin.example.com:8080"]`,
 		Enabled:   true,
@@ -204,8 +200,6 @@ func TestBuildCurrentConfigBundleEnablesGlobalPoWWithoutExplicitBinding(t *testi
 
 	route := &model.ProxyRoute{
 		SiteName:  "pow-global.example.com",
-		Domain:    "pow-global.example.com",
-		Domains:   `["pow-global.example.com"]`,
 		OriginURL: "http://origin.example.com:8080",
 		Upstreams: `["http://origin.example.com:8080"]`,
 		Enabled:   true,

internal/apps/openflare/config_version/pages_snapshot_test.go

@@ -45,8 +45,6 @@ func TestBuildSnapshotRoutesPages(t *testing.T) {
 
 	route := &model.ProxyRoute{
 		SiteName:       "speedtest",
-		Domain:         "speedtest.arctel.net",
-		Domains:        `["speedtest.arctel.net"]`,
 		OriginURL:      "openflare-pages://project/1",
 		Upstreams:      `["openflare-pages://project/1"]`,
 		Enabled:        true,