feat(acceptance): 建立同构验收与弹性容量体系

实现本地三节点 K3s 同构环境、脱敏生产快照、Gemini 图片和多参考图视频协议模拟、统一验收报告及故障注入。\n\n新增 Worker 容量控制器、资源与连接预算、任务恢复保护，并将生产验收拆分为 validation 执行和人工 CAS 放量。\n\n验证包括 Go 全量测试、PostgreSQL HTTP 集成测试、go vet、OpenAPI、ShellCheck、前端检查、迁移及发布脚本测试。

apps/api/internal/identity/configuration_test.go

@@ -226,3 +226,27 @@ func TestApplyManifestV2RemovesFixedTenantMappingWhileV1StillRequiresIt(t *testi
 		t.Fatal("Manifest V1 without a fixed local tenant mapping was accepted")
 	}
 }
+
+func TestApplyManifestV1PersistsSingleTenantMode(t *testing.T) {
+	draft, err := NewDraft(PairingInput{
+		AuthCenterURL: "https://auth.example.com", PublicBaseURL: "https://api.example.com",
+		WebBaseURL: "https://gateway.example.com", LocalTenantKey: "default",
+	}, "production")
+	if err != nil {
+		t.Fatal(err)
+	}
+	applied, err := ApplyManifest(draft, ManifestApplication{
+		AppEnv: "production",
+		Manifest: ManifestV1{
+			SchemaVersion: 1, Issuer: "https://auth.example.com/issuer/default",
+			TenantID: "aaaaaaaa-aaaa-aaaa-aaaa-aaaaaaaaaaaa", ApplicationID: "bbbbbbbb-bbbb-bbbb-bbbb-bbbbbbbbbbbb",
+			Capabilities: []string{}, Scopes: []string{}, Clients: ManifestClients{},
+		},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if applied.TenantMode != "single_tenant" {
+		t.Fatalf("Manifest V1 should persist the explicit single-tenant discriminator: %#v", applied)
+	}
+}