feat: harden support, localize knowledge and add operator availability [skip ci]

Source-only publication of reviewed commit 64e96a7f423673dc29ad56485be9fc79bce8af1c.

Passed in isolation: focused frontend/backend tests, race checks, TypeScript typecheck, lint, Go compilation, Flowgram build, and deterministic SDK build/tests.

Not accepted as a production release: Next.js export/native assembly remains blocked by environment memory limits; browser interaction and MySQL staging acceptance remain unverified. No production server, database/schema, runtime configuration, deployment, release tag, or workflow execution was performed.

Expected source tree: 0a4a7528e9.

internal/services/knowledge_base_service_test.go

@@ -1,3 +1,4 @@
+// Modified in the independent AgentDesk fork: localized knowledge workflows and safe display errors.
 package services
 
 import (
@@ -10,6 +11,7 @@ import (
 	"agent-desk/internal/models"
 	"agent-desk/internal/pkg/dto/request"
 	"agent-desk/internal/pkg/enums"
+	"agent-desk/internal/pkg/errorsx"
 	"agent-desk/internal/repositories"
 
 	"github.com/glebarez/sqlite"
@@ -203,3 +205,36 @@ func assertKnowledgeBaseServiceTestCount(t *testing.T, model any, query string,
 		t.Fatalf("count %T = %d, want %d", model, count, want)
 	}
 }
+
+func TestDeleteKnowledgeBaseWorkflowErrorsLocalized(t *testing.T) {
+	for _, count := range []int{1, 2} {
+		t.Run(string(rune('0'+count)), func(t *testing.T) {
+			setupKnowledgeBaseServiceTestDB(t)
+			kb := createKnowledgeBaseServiceTestBase(t, "Keep this knowledge base")
+			for i := 0; i < count; i++ {
+				createKnowledgeBaseServiceTestWorkflow(t, "流程 %s / Процесс"+string(rune('A'+i)), knowledgeBaseServiceTestWorkflowDefinition([]int64{kb.ID}))
+			}
+			err := KnowledgeBaseService.DeleteKnowledgeBase(kb.ID)
+			localized, ok := err.(*errorsx.I18nError)
+			if !ok {
+				t.Fatalf("expected localized application error, got %T: %v", err, err)
+			}
+			key := "error.knowledge.workflowReference"
+			if count > 1 {
+				key = "error.knowledge.workflowReferences"
+			}
+			if localized.Key != key {
+				t.Fatalf("error key = %q", localized.Key)
+			}
+			for _, locale := range []string{"en-US", "ru-RU"} {
+				message := localized.Message(locale)
+				if strings.Contains(message, "%!") || strings.Contains(message, "error.knowledge") || strings.Contains(message, "知识库正在") {
+					t.Fatalf("bad localized message %q", message)
+				}
+				if count == 1 && !strings.Contains(message, "流程 %s / Процесс") {
+					t.Fatalf("workflow name changed: %q", message)
+				}
+			}
+		})
+	}
+}