refactor(data): add mock API adapters, id utility, and toast feedback

store/chat.ts

@@ -1,4 +1,5 @@
 import { create } from "zustand"
+import { generateId } from "@/lib/id"
 import { mockChatMessages, mockChatSessions, mockUsers } from "@/lib/mock"
 import type { ChatMessage, ChatSession, Order } from "@/lib/types"
 
@@ -76,7 +77,7 @@ export const useChatStore = create<ChatState>((set, get) => ({
 
     const now = new Date().toISOString()
     const message: ChatMessage = {
-      id: `msg-${Date.now()}`,
+      id: generateId("msg"),
       sessionId,
       senderId: sender.id,
       senderName: sender.name,