fix: 第3轮调试Bug修复 (P1: 弱随机+crypto/rand, Knowledge键对齐; P2: 简报created_at, CORS+安全头)

backend/gateway/internal/middleware/cors.go

@@ -6,15 +6,28 @@ import (
 	"github.com/gin-gonic/gin"
 )
 
-// CORS 跨域中间件
+// CORS 跨域中间件 (含安全头)
 func CORS() gin.HandlerFunc {
 	return func(c *gin.Context) {
-		c.Header("Access-Control-Allow-Origin", "*")
+		origin := c.Request.Header.Get("Origin")
+		if origin == "" {
+			origin = "*"
+		}
+		c.Header("Access-Control-Allow-Origin", origin)
 		c.Header("Access-Control-Allow-Methods", "GET, POST, PUT, DELETE, PATCH, OPTIONS")
 		c.Header("Access-Control-Allow-Headers", "Origin, Content-Type, Authorization, X-Request-ID")
 		c.Header("Access-Control-Allow-Credentials", "true")
 		c.Header("Access-Control-Max-Age", "86400")
 
+		// 安全头
+		c.Header("X-Content-Type-Options", "nosniff")
+		c.Header("X-Frame-Options", "DENY")
+		c.Header("X-XSS-Protection", "1; mode=block")
+		c.Header("Referrer-Policy", "strict-origin-when-cross-origin")
+		c.Header("Permissions-Policy", "camera=(), microphone=(), geolocation=()")
+		c.Header("Content-Security-Policy", "default-src 'self'; script-src 'self' 'unsafe-inline' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data: https:; connect-src 'self' https:; font-src 'self'; object-src 'none'")
+		c.Header("Strict-Transport-Security", "max-age=31536000; includeSubDomains")
+
 		// 预检请求
 		if c.Request.Method == http.MethodOptions {
 			c.AbortWithStatus(http.StatusNoContent)