feat: 添加小红书Feed评论功能 (#50)

实现通过HTTP GIN API和MCP API发表评论到小红书Feed的功能：
- 新增POST /api/v1/feeds/comment端点
- 新增post_comment_to_feed MCP工具
- 添加PostCommentRequest和PostCommentResponse类型
- 实现PostCommentToFeed服务方法
- 新增CommentFeedAction用于浏览器自动化操作

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-authored-by: Claude <noreply@anthropic.com>

streamable_http.go

@@ -233,6 +233,28 @@ func (s *AppServer) processToolsList(request *JSONRPCRequest) *JSONRPCResponse {
 				"required": []string{"feed_id", "xsec_token"},
 			},
 		},
+		{
+			"name":        "post_comment_to_feed",
+			"description": "发表评论到小红书笔记",
+			"inputSchema": map[string]interface{}{
+				"type": "object",
+				"properties": map[string]interface{}{
+					"feed_id": map[string]interface{}{
+						"type":        "string",
+						"description": "小红书笔记ID，从Feed列表获取",
+					},
+					"xsec_token": map[string]interface{}{
+						"type":        "string",
+						"description": "访问令牌，从Feed列表的xsecToken字段获取",
+					},
+					"content": map[string]interface{}{
+						"type":        "string",
+						"description": "评论内容",
+					},
+				},
+				"required": []string{"feed_id", "xsec_token", "content"},
+			},
+		},
 	}
 
 	return &JSONRPCResponse{
@@ -275,6 +297,8 @@ func (s *AppServer) processToolCall(ctx context.Context, request *JSONRPCRequest
 		result = s.handleSearchFeeds(ctx, toolArgs)
 	case "get_feed_detail":
 		result = s.handleGetFeedDetail(ctx, toolArgs)
+	case "post_comment_to_feed":
+		result = s.handlePostComment(ctx, toolArgs)
 	default:
 		return &JSONRPCResponse{
 			JSONRPC: "2.0",