feat(seller-team): split buyer inbox vs store inbox in chat UI

Seller dashboard threads (type="store") now fetch the store's inbox via
useGetStoreThreads(storeId) -> /threads/list/?store_id=; the profile threads page
(type="user") keeps the personal buyer inbox. Depends on the seller-team backend
(store-aware threads + store_id-by-username), so it ships on this branch, not main.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

app/components/thread/ThreadsPage.tsx

@@ -1,7 +1,10 @@
 import { Link } from "@remix-run/react";
 import AppInput from "../AppInput";
 import { useState } from "react";
-import { useGetUserThreads } from "../../requestHandler/use-chat-hooks";
+import {
+  useGetUserThreads,
+  useGetStoreThreads,
+} from "../../requestHandler/use-chat-hooks";
 import {
   ThreadList,
   ThreadParticipant,
@@ -20,7 +23,16 @@ interface ThreadsPageProps {
 
 export default function ThreadsPage({ type, storeId }: ThreadsPageProps) {
   const [searchValue, setSearchValue] = useState("");
-  const { data: threads, isLoading, isError, refetch } = useGetUserThreads();
+  // Seller dashboard shows the STORE's inbox; the profile page shows the user's
+  // personal (buyer) chats. Two different endpoints so the two never mix.
+  const userThreads = useGetUserThreads();
+  const storeThreads = useGetStoreThreads(type === "store" ? storeId : undefined);
+  const {
+    data: threads,
+    isLoading,
+    isError,
+    refetch,
+  } = type === "store" ? storeThreads : userThreads;
   const sortedThreads = threads?.sort((a, b) => {
     const dateA = new Date(a.lastMessageTime || "2025-01-18T00:00:00.000Z");
     const dateB = new Date(b.lastMessageTime || "2025-01-18T00:00:00.000Z");

app/requestHandler/use-chat-hooks.tsx

@@ -31,6 +31,30 @@ export function useGetUserThreads() {
   });
 }
 
+/**
+ * List a STORE's inbox (owner + staff), scoped to the store's own threads.
+ * Distinct from useGetUserThreads(), which returns the user's personal buyer chats.
+ */
+export function useGetStoreThreads(storeId?: string) {
+  const token = useAuthToken();
+
+  return useQuery({
+    queryKey: ["getStoreThreads", storeId],
+    queryFn: async () => {
+      if (!token) {
+        throw new Error("Authentication token is required");
+      }
+      const chatApi = createChatApi(token);
+      return await chatApi.apiChatV1ThreadsListList({ storeId });
+    },
+    enabled: !!token && !!storeId,
+    retry: 1,
+    retryDelay: 3000,
+    refetchOnWindowFocus: false,
+    refetchInterval: 20 * 1000,
+  });
+}
+
 /**
  * Server-side function to get thread details
  */