feat: 脚本创作+发布+市场体系

- 数据模型新增: title(必填), description(可选), status(draft/published)
- 新增 API: POST /scripts/:id/publish, GET /api/market (搜索+分页+runtime过滤)
- 前端首页重构: 选语言 → CodeMirror 编辑器(8种语言语法高亮) → 标题/描述 → 草稿/发布
- 新增 /market 页面: 浏览已发布脚本, 搜索+过滤+分页
- 详情页新增: 发布按钮(草稿→市场), title/description 展示
- Shell 类运行时显示 source 命令(继承环境变量)
- backend GetSourceCommand 支持 bash/zsh/sh/fish 四种 shell 格式

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/cmd/server/main.go

@@ -38,7 +38,9 @@ func main() {
 		api.Use(middleware.RateLimit(60))
 		api.POST("/scripts", middleware.RateLimit(10), handler.CreateScript(svc))
 		api.GET("/scripts/:id", handler.GetScript(svc))
+		api.POST("/scripts/:id/publish", handler.PublishScript(svc))
 		api.DELETE("/scripts/:id", handler.DeleteScript(svc))
+		api.GET("/market", handler.ListMarket(svc))
 	}
 
 	r.GET("/raw/:id", handler.GetRawScript(svc))