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.

web/app/(dashboard)/dashboard/conversations/_components/agent-message-editor.tsx

@@ -1,3 +1,5 @@
+// Modified in the independent hardening fork; see docs/hardening/README.md.
+// Modified for AgentDeskFixes: retain operator drafts and forward pending-send state.
 "use client"
 
 import { useEffect, useRef, useState } from "react"
@@ -11,11 +13,14 @@ import {
   sendOperatorPresence,
   useAgentConversationsStore,
 } from "@/hooks/use-agent-conversation-realtime"
+import type { MessageEditorDraftStore } from "@/lib/message-editor-drafts"
 import { useI18n } from "@/i18n/provider"
 import { fetchQuickReplyListAll, type AdminQuickReply } from "@/lib/api/admin"
 import { suggestAgentReply } from "@/lib/api/agent"
 
 type AgentMessageEditorProps = {
+  draftStore: MessageEditorDraftStore
+  sending?: boolean
   disabled?: boolean
   uploadingAsset?: boolean
   onSend: (html: string) => Promise<void>
@@ -28,6 +33,8 @@ type AgentMessageEditorProps = {
  * Supports quick replies picker and slash command (/) autocomplete.
  */
 export function AgentMessageEditor({
+  draftStore,
+  sending = false,
   disabled = false,
   uploadingAsset = false,
   onSend,
@@ -79,6 +86,8 @@ export function AgentMessageEditor({
     <SharedMessageEditor
       variant="agent"
       conversationId={selectedConversationId}
+      draftStore={draftStore}
+      sending={sending}
       disabled={disabled}
       uploadingAsset={uploadingAsset}
       quickReplies={{