feat(welcome): 站点外观 - 合并欢迎页开放开关与入口分包修复

# Conflicts:
#	docs/content/docs/progress/pending-test.mdx

web/src/pages/admin/components/feature-availability-panel.tsx

@@ -368,6 +368,7 @@ function parseFeatureAvailability(value: unknown): FeatureAvailability {
         if (typeof record[key] !== "boolean") throw new Error("功能开放配置响应缺少有效开关状态");
     }
     return {
+        welcomeEnabled: record.welcomeEnabled as boolean,
         shortDramaEnabled: record.shortDramaEnabled as boolean,
         taskCenterEnabled: record.taskCenterEnabled as boolean,
         creditsEnabled: record.creditsEnabled as boolean,

web/src/pages/admin/settings/appearance-settings-page.tsx

@@ -9,6 +9,7 @@ import { AdminStatusBadge, SettingsSectionCard } from "@/pages/admin/components/
 import { cn } from "@/lib/utils";
 import { cloneSkinDefinition, DEFAULT_CLASSIC_SKIN, duplicateSkinDefinition, normalizeSkinDefinition, type SkinDefinition } from "@/lib/skin-themes";
 import { SkinThemeEditor } from "@/pages/admin/settings/components/skin-theme-editor";
+import { WelcomeSetting } from "@/pages/admin/settings/components/welcome-setting";
 import { deleteAdminResources } from "@/services/api/admin-storage";
 import { getAdminAppearance, resetAdminAppearance, updateAdminAppearance, uploadAppearanceAsset, type AdminAppearance, type AppearanceAssetSlot } from "@/services/api/appearance";
 import { commitPublicAppearance, DEFAULT_PUBLIC_APPEARANCE } from "@/stores/use-appearance-store";
@@ -473,6 +474,7 @@ export default function AppearanceSettingsPage() {
                                         onChange={(event) => setBrandSlug(event.target.value.toLocaleLowerCase().replace(/[^a-z0-9-]/g, ""))}
                                     />
                                 </Form.Item>
+                                <WelcomeSetting />
                             </Form>
                             <div className="admin-appearance-brand-logo admin-appearance-logo-stack">
                                 <AssetPicker

web/src/pages/admin/settings/components/welcome-setting.tsx

@@ -0,0 +1,65 @@
+import { useEffect, useState } from "react";
+import { App, Button } from "antd";
+import { Switch } from "@/components/ui/base/switch";
+import { getAdminFeatureAvailability, updateAdminFeatureAvailability } from "@/services/api/auth";
+import { useUserStore } from "@/stores/use-user-store";
+
+export function WelcomeSetting() {
+    const { message } = App.useApp();
+    const [enabled, setEnabled] = useState<boolean | null>(null);
+    const [saving, setSaving] = useState(false);
+    const [error, setError] = useState("");
+    const [revision, setRevision] = useState(0);
+    const setFeatures = useUserStore((state) => state.setFeatures);
+
+    useEffect(() => {
+        let active = true;
+        setError("");
+        getAdminFeatureAvailability()
+            .then(({ features }) => {
+                if (typeof features.welcomeEnabled !== "boolean") throw new Error("欢迎页配置无效");
+                if (active) setEnabled(features.welcomeEnabled);
+            })
+            .catch(() => {
+                if (active) setError("读取欢迎页状态失败，请重试。");
+            });
+        return () => {
+            active = false;
+        };
+    }, [revision]);
+
+    async function changeWelcome(value: boolean) {
+        if (saving) return;
+        setSaving(true);
+        try {
+            const { features } = await updateAdminFeatureAvailability({ welcomeEnabled: value });
+            if (features.welcomeEnabled !== value) throw new Error("欢迎页状态未保存，请重试");
+            setEnabled(features.welcomeEnabled);
+            setFeatures(features);
+            message.success(value ? "欢迎页已启用" : "欢迎页已关闭");
+        } catch (error) {
+            message.error(error instanceof Error ? error.message : "保存欢迎页状态失败");
+        } finally {
+            setSaving(false);
+        }
+    }
+
+    return (
+        <div className="admin-appearance-logo-frame-option">
+            <div className="admin-appearance-logo-frame-copy">
+                <strong>启用欢迎页</strong>
+                <p>切换后立即保存。关闭后访问 /welcome 将跳转到首页。</p>
+                {error ? (
+                    <div role="alert">
+                        {error}
+                        <Button onClick={() => setRevision((value) => value + 1)}>重试</Button>
+                    </div>
+                ) : null}
+            </div>
+            <div className="admin-appearance-logo-frame-control">
+                <span>{enabled === null ? "读取中" : saving ? "保存中" : enabled ? "已启用" : "已关闭"}</span>
+                <Switch aria-label="启用欢迎页" checked={enabled === true} disabled={enabled === null || saving || Boolean(error)} onChange={(value) => void changeWelcome(value)} />
+            </div>
+        </div>
+    );
+}