📦 添加虚拟环境和启动脚本

新增:
- backend/venv/ - Python 虚拟环境
- backend/start.sh - 启动脚本（使用虚拟环境）
- backend/requirements.txt - 依赖列表
- .gitignore - 忽略虚拟环境和缓存文件

说明:
- 每个项目使用独立虚拟环境
- 避免依赖冲突
- 启动脚本自动创建和激活虚拟环境

frontend/node_modules/@nodelib/fs.stat/out/providers/async.d.ts

@@ -0,0 +1,4 @@
+import type Settings from '../settings';
+import type { ErrnoException, Stats } from '../types';
+export declare type AsyncCallback = (error: ErrnoException, stats: Stats) => void;
+export declare function read(path: string, settings: Settings, callback: AsyncCallback): void;

frontend/node_modules/@nodelib/fs.stat/out/providers/async.js

@@ -0,0 +1,36 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.read = void 0;
+function read(path, settings, callback) {
+    settings.fs.lstat(path, (lstatError, lstat) => {
+        if (lstatError !== null) {
+            callFailureCallback(callback, lstatError);
+            return;
+        }
+        if (!lstat.isSymbolicLink() || !settings.followSymbolicLink) {
+            callSuccessCallback(callback, lstat);
+            return;
+        }
+        settings.fs.stat(path, (statError, stat) => {
+            if (statError !== null) {
+                if (settings.throwErrorOnBrokenSymbolicLink) {
+                    callFailureCallback(callback, statError);
+                    return;
+                }
+                callSuccessCallback(callback, lstat);
+                return;
+            }
+            if (settings.markSymbolicLink) {
+                stat.isSymbolicLink = () => true;
+            }
+            callSuccessCallback(callback, stat);
+        });
+    });
+}
+exports.read = read;
+function callFailureCallback(callback, error) {
+    callback(error);
+}
+function callSuccessCallback(callback, result) {
+    callback(null, result);
+}

frontend/node_modules/@nodelib/fs.stat/out/providers/sync.d.ts

@@ -0,0 +1,3 @@
+import type Settings from '../settings';
+import type { Stats } from '../types';
+export declare function read(path: string, settings: Settings): Stats;

frontend/node_modules/@nodelib/fs.stat/out/providers/sync.js

@@ -0,0 +1,23 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.read = void 0;
+function read(path, settings) {
+    const lstat = settings.fs.lstatSync(path);
+    if (!lstat.isSymbolicLink() || !settings.followSymbolicLink) {
+        return lstat;
+    }
+    try {
+        const stat = settings.fs.statSync(path);
+        if (settings.markSymbolicLink) {
+            stat.isSymbolicLink = () => true;
+        }
+        return stat;
+    }
+    catch (error) {
+        if (!settings.throwErrorOnBrokenSymbolicLink) {
+            return lstat;
+        }
+        throw error;
+    }
+}
+exports.read = read;