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/ai/rag/index_retrieve_helpers_test.go

@@ -1,9 +1,13 @@
+// Modified in the independent AgentDesk fork: localized knowledge workflows and safe display errors.
 package rag
 
 import (
+	"context"
 	"strings"
 	"testing"
 
+	"agent-desk/internal/pkg/i18nx"
+
 	"agent-desk/internal/models"
 )
 
@@ -14,7 +18,7 @@ func TestBuildFAQChunkContent(t *testing.T) {
 		Answer:           "在订单页发起退款。",
 	}
 
-	content := buildFAQChunkContent(faq)
+	content := sourceFAQContent(faq).render(i18nx.LocaleZhCN)
 	if !strings.Contains(content, "问题：如何退款") {
 		t.Fatalf("expected question in content, got %q", content)
 	}
@@ -70,7 +74,7 @@ func TestNormalizeContextResultsMergesAndDedupes(t *testing.T) {
 }
 
 func TestBuildContextChunkText(t *testing.T) {
-	faqText := buildContextChunkText(RetrieveResult{
+	faqText := buildContextChunkText(i18nx.WithLocale(context.Background(), i18nx.LocaleZhCN), RetrieveResult{
 		FaqID:       1,
 		FaqQuestion: "如何退款",
 		Content:     "在订单页发起退款。",
@@ -79,7 +83,7 @@ func TestBuildContextChunkText(t *testing.T) {
 		t.Fatalf("unexpected faq context text: %q", faqText)
 	}
 
-	docText := buildContextChunkText(RetrieveResult{
+	docText := buildContextChunkText(i18nx.WithLocale(context.Background(), i18nx.LocaleZhCN), RetrieveResult{
 		DocumentID:    2,
 		DocumentTitle: "退款文档",
 		SectionPath:   "售后/退款",