feat(canvas): 绘图工具 - 集成 Excalidraw 并支持后台切换默认引擎

web/src/pages/admin/components/admin-shell.tsx

@@ -1,5 +1,5 @@
 import { Tooltip } from "antd";
-import { ArrowLeft, BarChart3, BellRing, Coins, FileClock, HardDrive, Home, Infinity as InfinityIcon, Mail, MessageSquareText, PanelLeftClose, PanelLeftOpen, RadioTower, Settings2, ShieldCheck, TicketCheck, UsersRound } from "lucide-react";
+import { ArrowLeft, BarChart3, BellRing, Coins, FileClock, HardDrive, Home, Infinity as InfinityIcon, Mail, MessageSquareText, Paintbrush, PanelLeftClose, PanelLeftOpen, RadioTower, Settings2, ShieldCheck, TicketCheck, UsersRound } from "lucide-react";
 import { useState, type ReactNode } from "react";
 import { Link, NavLink, Outlet } from "react-router";
 
@@ -40,6 +40,7 @@ const adminNavigation: Array<{ label: string; items: AdminNavigationItem[] }> =
     {
         label: "系统配置",
         items: [
+            { path: "/admin/settings/drawing-engine", label: "绘图工具", description: "画布绘图节点默认引擎", icon: <Paintbrush className="size-4" /> },
             { path: "/admin/settings/runtime-policy", label: "资源与策略", description: "配额、并发、频控与超时", icon: <Settings2 className="size-4" /> },
             { path: "/admin/settings/access", label: "登录与注册", description: "注册策略与 Linux.do", icon: <ShieldCheck className="size-4" /> },
             { path: "/admin/settings/email", label: "邮件服务", description: "注册验证码 SMTP", icon: <Mail className="size-4" /> },

web/src/pages/admin/settings/drawing-engine-settings-page.tsx

@@ -0,0 +1,75 @@
+import { App, Button, Segmented, Tag } from "antd";
+import { Brush, Save } from "lucide-react";
+import { useEffect, useState } from "react";
+
+import { drawingEngineLabel, isDrawingEngineAvailable, type CanvasDrawingEngine } from "@/lib/canvas/canvas-drawing-engine";
+import { getAdminDrawingEngineSetting, updateAdminDrawingEngineSetting } from "@/services/api/auth";
+import { useUserStore } from "@/stores/use-user-store";
+import { AdminPageFrame } from "../components/admin-shell";
+import { SettingsSectionCard } from "../components/admin-ui";
+
+export default function DrawingEngineSettingsPage() {
+    const { message } = App.useApp();
+    const current = useUserStore((state) => state.drawingEngine);
+    const setDrawingEngine = useUserStore((state) => state.setDrawingEngine);
+    const [engine, setEngine] = useState<CanvasDrawingEngine>(current.defaultEngine);
+    const [loading, setLoading] = useState(true);
+    const [saving, setSaving] = useState(false);
+
+    useEffect(() => {
+        let cancelled = false;
+        void getAdminDrawingEngineSetting().then(({ setting }) => {
+            if (cancelled) return;
+            setDrawingEngine(setting);
+            setEngine(setting.defaultEngine);
+        }).catch((error) => {
+            if (!cancelled) message.error(error instanceof Error ? error.message : "读取绘图工具配置失败");
+        }).finally(() => {
+            if (!cancelled) setLoading(false);
+        });
+        return () => { cancelled = true; };
+    }, [message, setDrawingEngine]);
+
+    const save = async () => {
+        if (!isDrawingEngineAvailable(engine)) {
+            message.error("当前生产构建未配置 tldraw License Key");
+            return;
+        }
+        setSaving(true);
+        try {
+            const { setting } = await updateAdminDrawingEngineSetting(engine);
+            setDrawingEngine(setting);
+            setEngine(setting.defaultEngine);
+            message.success("默认绘图工具已更新");
+        } catch (error) {
+            message.error(error instanceof Error ? error.message : "保存绘图工具配置失败");
+        } finally {
+            setSaving(false);
+        }
+    };
+
+    const dirty = engine !== current.defaultEngine;
+    return (
+        <AdminPageFrame title="绘图工具" description="设置新建绘图节点使用的默认编辑器">
+            <div className="mx-auto max-w-4xl space-y-5">
+                <SettingsSectionCard icon={<Brush className="size-4" />} title="默认绘图引擎" description="已有绘图保持原引擎，仅新建绘图使用这里的选择。" status={<Tag variant="filled" color="blue">{drawingEngineLabel(current.defaultEngine)}</Tag>}>
+                    <div className="flex flex-col gap-4 px-5 py-5 sm:flex-row sm:items-center sm:justify-between">
+                        <Segmented<CanvasDrawingEngine>
+                            block
+                            className="w-full sm:max-w-md"
+                            disabled={loading || saving}
+                            value={engine}
+                            onChange={setEngine}
+                            options={[
+                                { label: "Excalidraw", value: "excalidraw" },
+                                { label: "tldraw", value: "tldraw", disabled: !isDrawingEngineAvailable("tldraw") },
+                            ]}
+                        />
+                        <Button type="primary" icon={<Save className="size-4" />} loading={saving} disabled={loading || !dirty} onClick={() => void save()}>保存配置</Button>
+                    </div>
+                    {!isDrawingEngineAvailable("tldraw") ? <div className="border-t border-border px-5 py-3 text-xs text-amber-600 dark:text-amber-400">当前生产构建没有 tldraw License Key，不能将其设为新建默认值。</div> : null}
+                </SettingsSectionCard>
+            </div>
+        </AdminPageFrame>
+    );
+}