fix: use hostname:8000 as API fallback for remote deployments

Replace hardcoded localhost:8000 with window.location.hostname:8000 so the
frontend auto-detects the correct backend address when deployed on a remote
server instead of always pointing to localhost.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

web/src/components/home/navbar.tsx

@@ -20,7 +20,7 @@ const NAV_LINKS = [
   { href: "/chat", label: "智能问答", icon: MessageSquare },
   { href: "/knowledge", label: "知识库", icon: Database },
   { href: "/spatial", label: "空间设计", icon: Image },
-  { href: "/forum", label: "课程社区", icon: Users },
+  { href: "/forum", label: "课程社区", icon: Users, requireAuth: true },
   { href: "/admin", label: "后台管理", icon: ShieldCheck, adminOnly: true },
 ];
 
@@ -80,28 +80,6 @@ export default function Navbar({ isAuthenticated, user }: NavbarProps) {
             </div>
           )}
 
-          {/* 未登录时也显示课程社区链接 */}
-          {!isAuthenticated && (
-            <div className="hidden md:flex items-center h-full -mb-px">
-              <Link
-                href="/forum"
-                className={`
-                  relative flex items-center gap-1.5 px-3 h-full text-sm transition-colors
-                  ${isActive("/forum")
-                    ? "text-primary font-medium"
-                    : "text-muted-foreground hover:text-foreground"
-                  }
-                `}
-              >
-                <Users className="w-4 h-4" />
-                <span>课程社区</span>
-                {isActive("/forum") && (
-                  <span className="absolute bottom-0 left-3 right-3 h-0.5 bg-primary rounded-full" />
-                )}
-              </Link>
-            </div>
-          )}
-
           <div className="flex items-center space-x-3">
             <ThemeToggle />
 

web/src/components/layout/mobile-nav.tsx

@@ -20,11 +20,11 @@ import {
 } from "lucide-react";
 
 const navItems = [
-  { id: "course-content", name: "课程内容", icon: GraduationCap, href: "/course-content" },
-  { id: "chat", name: "对话", icon: MessageSquare, href: "/chat" },
-  { id: "knowledge", name: "知识库", icon: BookOpen, href: "/knowledge" },
-  { id: "spatial", name: "空间出图", icon: Image, href: "/spatial" },
-  { id: "forum", name: "社区", icon: Users, href: "/forum" },
+  { id: "course-content", name: "课程内容", icon: GraduationCap, href: "/course-content", requireAuth: true },
+  { id: "chat", name: "对话", icon: MessageSquare, href: "/chat", requireAuth: true },
+  { id: "knowledge", name: "知识库", icon: BookOpen, href: "/knowledge", requireAuth: true },
+  { id: "spatial", name: "空间出图", icon: Image, href: "/spatial", requireAuth: true },
+  { id: "forum", name: "社区", icon: Users, href: "/forum", requireAuth: true },
 ];
 
 export default function MobileNav() {
@@ -47,9 +47,10 @@ export default function MobileNav() {
   return (
     <>
       {/* Bottom navigation bar */}
+      {user && (
       <div className="lg:hidden fixed bottom-0 left-0 right-0 bg-background border-t border-border mobile-safe-area z-50">
         <div className="flex items-center justify-around py-2">
-          {navItems.map((item) => {
+          {navItems.filter(item => !item.requireAuth || user).map((item) => {
             const isActive = pathname === item.href;
             return (
               <Button
@@ -68,6 +69,7 @@ export default function MobileNav() {
           })}
         </div>
       </div>
+      )}
 
       {/* Menu toggle button */}
       <div className="lg:hidden fixed top-4 right-4 z-50">
@@ -108,7 +110,7 @@ export default function MobileNav() {
               {/* Navigation */}
               <div className="flex-1 p-6">
                 <nav className="space-y-2">
-                  {navItems.map((item) => {
+                  {navItems.filter(item => !item.requireAuth || user).map((item) => {
                     const isActive = pathname === item.href;
                     return (
                       <Button

web/src/lib/api.ts

@@ -12,7 +12,7 @@ import type {
 } from "@/types";
 
 // API基础配置
-const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || (typeof window !== 'undefined' ? `${window.location.protocol}//${window.location.host}/api` : "http://127.0.0.1:8000");
+const API_BASE_URL = process.env.NEXT_PUBLIC_API_URL || (typeof window !== 'undefined' ? `${window.location.protocol}//${window.location.hostname}:8000` : "http://127.0.0.1:8000");
 
 // 请求拦截器
 async function apiRequest<T>(