📦 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/core-js-pure/es/number/constructor.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.constructor');
+var path = require('../../internals/path');
+
+module.exports = path.Number;

frontend/node_modules/core-js-pure/es/number/epsilon.js

@@ -0,0 +1,4 @@
+'use strict';
+require('../../modules/es.number.epsilon');
+
+module.exports = Math.pow(2, -52);

frontend/node_modules/core-js-pure/es/number/index.js

@@ -0,0 +1,17 @@
+'use strict';
+require('../../modules/es.number.constructor');
+require('../../modules/es.number.epsilon');
+require('../../modules/es.number.is-finite');
+require('../../modules/es.number.is-integer');
+require('../../modules/es.number.is-nan');
+require('../../modules/es.number.is-safe-integer');
+require('../../modules/es.number.max-safe-integer');
+require('../../modules/es.number.min-safe-integer');
+require('../../modules/es.number.parse-float');
+require('../../modules/es.number.parse-int');
+require('../../modules/es.number.to-exponential');
+require('../../modules/es.number.to-fixed');
+require('../../modules/es.number.to-precision');
+var path = require('../../internals/path');
+
+module.exports = path.Number;

frontend/node_modules/core-js-pure/es/number/is-finite.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.is-finite');
+var path = require('../../internals/path');
+
+module.exports = path.Number.isFinite;

frontend/node_modules/core-js-pure/es/number/is-integer.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.is-integer');
+var path = require('../../internals/path');
+
+module.exports = path.Number.isInteger;

frontend/node_modules/core-js-pure/es/number/is-nan.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.is-nan');
+var path = require('../../internals/path');
+
+module.exports = path.Number.isNaN;

frontend/node_modules/core-js-pure/es/number/is-safe-integer.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.is-safe-integer');
+var path = require('../../internals/path');
+
+module.exports = path.Number.isSafeInteger;

frontend/node_modules/core-js-pure/es/number/max-safe-integer.js

@@ -0,0 +1,4 @@
+'use strict';
+require('../../modules/es.number.max-safe-integer');
+
+module.exports = 0x1FFFFFFFFFFFFF;

frontend/node_modules/core-js-pure/es/number/min-safe-integer.js

@@ -0,0 +1,4 @@
+'use strict';
+require('../../modules/es.number.min-safe-integer');
+
+module.exports = -0x1FFFFFFFFFFFFF;

frontend/node_modules/core-js-pure/es/number/parse-float.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.parse-float');
+var path = require('../../internals/path');
+
+module.exports = path.Number.parseFloat;

frontend/node_modules/core-js-pure/es/number/parse-int.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.parse-int');
+var path = require('../../internals/path');
+
+module.exports = path.Number.parseInt;

frontend/node_modules/core-js-pure/es/number/to-exponential.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.to-exponential');
+var entryUnbind = require('../../internals/entry-unbind');
+
+module.exports = entryUnbind('Number', 'toExponential');

frontend/node_modules/core-js-pure/es/number/to-fixed.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.to-fixed');
+var entryUnbind = require('../../internals/entry-unbind');
+
+module.exports = entryUnbind('Number', 'toFixed');

frontend/node_modules/core-js-pure/es/number/to-precision.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../modules/es.number.to-precision');
+var entryUnbind = require('../../internals/entry-unbind');
+
+module.exports = entryUnbind('Number', 'toPrecision');

frontend/node_modules/core-js-pure/es/number/virtual/index.js

@@ -0,0 +1,7 @@
+'use strict';
+require('../../../modules/es.number.to-exponential');
+require('../../../modules/es.number.to-fixed');
+require('../../../modules/es.number.to-precision');
+var entryVirtual = require('../../../internals/entry-virtual');
+
+module.exports = entryVirtual('Number');

frontend/node_modules/core-js-pure/es/number/virtual/to-exponential.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-exponential');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toExponential');

frontend/node_modules/core-js-pure/es/number/virtual/to-fixed.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-fixed');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toFixed');

frontend/node_modules/core-js-pure/es/number/virtual/to-precision.js

@@ -0,0 +1,5 @@
+'use strict';
+require('../../../modules/es.number.to-precision');
+var getBuiltInPrototypeMethod = require('../../../internals/get-built-in-prototype-method');
+
+module.exports = getBuiltInPrototypeMethod('Number', 'toPrecision');