chore: 初始化仓库基线（AGENTS.md、git 规范、敏感文件排除）

server-go/internal/middleware/security.go

@@ -0,0 +1,20 @@
+package middleware
+
+import (
+	"github.com/gin-gonic/gin"
+)
+
+// SecurityHeaders 统一补齐 HTTP 安全响应头，缓解点击劫持、MIME 嗅探等风险
+func SecurityHeaders() gin.HandlerFunc {
+	return func(c *gin.Context) {
+		h := c.Writer.Header()
+		h.Set("X-Content-Type-Options", "nosniff")
+		h.Set("X-Frame-Options", "DENY")
+		h.Set("Referrer-Policy", "no-referrer")
+		// 限制内联脚本/样式以缓解 XSS；允许同源与必要的外部资源
+		h.Set("Content-Security-Policy", "default-src 'self'; img-src 'self' data: blob:; media-src 'self' blob:; style-src 'self' 'unsafe-inline'; script-src 'self' 'unsafe-inline'; connect-src 'self' ws: wss:; font-src 'self' data:; object-src 'none'; frame-ancestors 'none'")
+		// 仅在内网 HTTPS 网关后运行时生效；HTTP 下浏览器会忽略
+		h.Set("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
+		c.Next()
+	}
+}