📦 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/prelude-ls/lib/Num.js

@@ -0,0 +1,130 @@
+// Generated by LiveScript 1.6.0
+var max, min, negate, abs, signum, quot, rem, div, mod, recip, pi, tau, exp, sqrt, ln, pow, sin, tan, cos, asin, acos, atan, atan2, truncate, round, ceiling, floor, isItNaN, even, odd, gcd, lcm;
+max = curry$(function(x$, y$){
+  return x$ > y$ ? x$ : y$;
+});
+min = curry$(function(x$, y$){
+  return x$ < y$ ? x$ : y$;
+});
+negate = function(x){
+  return -x;
+};
+abs = Math.abs;
+signum = function(x){
+  if (x < 0) {
+    return -1;
+  } else if (x > 0) {
+    return 1;
+  } else {
+    return 0;
+  }
+};
+quot = curry$(function(x, y){
+  return ~~(x / y);
+});
+rem = curry$(function(x$, y$){
+  return x$ % y$;
+});
+div = curry$(function(x, y){
+  return Math.floor(x / y);
+});
+mod = curry$(function(x$, y$){
+  var ref$;
+  return ((x$) % (ref$ = y$) + ref$) % ref$;
+});
+recip = (function(it){
+  return 1 / it;
+});
+pi = Math.PI;
+tau = pi * 2;
+exp = Math.exp;
+sqrt = Math.sqrt;
+ln = Math.log;
+pow = curry$(function(x$, y$){
+  return Math.pow(x$, y$);
+});
+sin = Math.sin;
+tan = Math.tan;
+cos = Math.cos;
+asin = Math.asin;
+acos = Math.acos;
+atan = Math.atan;
+atan2 = curry$(function(x, y){
+  return Math.atan2(x, y);
+});
+truncate = function(x){
+  return ~~x;
+};
+round = Math.round;
+ceiling = Math.ceil;
+floor = Math.floor;
+isItNaN = function(x){
+  return x !== x;
+};
+even = function(x){
+  return x % 2 === 0;
+};
+odd = function(x){
+  return x % 2 !== 0;
+};
+gcd = curry$(function(x, y){
+  var z;
+  x = Math.abs(x);
+  y = Math.abs(y);
+  while (y !== 0) {
+    z = x % y;
+    x = y;
+    y = z;
+  }
+  return x;
+});
+lcm = curry$(function(x, y){
+  return Math.abs(Math.floor(x / gcd(x, y) * y));
+});
+module.exports = {
+  max: max,
+  min: min,
+  negate: negate,
+  abs: abs,
+  signum: signum,
+  quot: quot,
+  rem: rem,
+  div: div,
+  mod: mod,
+  recip: recip,
+  pi: pi,
+  tau: tau,
+  exp: exp,
+  sqrt: sqrt,
+  ln: ln,
+  pow: pow,
+  sin: sin,
+  tan: tan,
+  cos: cos,
+  acos: acos,
+  asin: asin,
+  atan: atan,
+  atan2: atan2,
+  truncate: truncate,
+  round: round,
+  ceiling: ceiling,
+  floor: floor,
+  isItNaN: isItNaN,
+  even: even,
+  odd: odd,
+  gcd: gcd,
+  lcm: lcm
+};
+function curry$(f, bound){
+  var context,
+  _curry = function(args) {
+    return f.length > 1 ? function(){
+      var params = args ? args.concat() : [];
+      context = bound ? context || this : this;
+      return params.push.apply(params, arguments) <
+          f.length && arguments.length ?
+        _curry.call(context, params) : f.apply(context, params);
+    } : f;
+  };
+  return _curry();
+}