feat: add xml_attribute matching config for payload_xml_value

This adds xml_attribute schema fields and example usage so XML extraction can be constrained by attribute name/value alongside existing match conditions.

Author: rvql

server/agent_config/custom_app.example.yaml

@@ -72,6 +72,26 @@ biz_field:
           value: 5
       output:
         attribute_name: "tlv_c5"
+    - name: "xml_attr_field"
+      type: "payload_xml_value"
+      match:
+        type: "string"
+        keyword: "data"
+        xml_attribute:
+          name: "name"
+          value: "TRAN_TIMESTAMP"
+          ignore_case: false
+      post:
+      - type: parse_xml_value
+        settings:
+        - key: keyword
+          value: "field"
+        - key: type
+          value: "string"
+        - key: ignore_case
+          value: false
+      output:
+        attribute_name: "xml_attr_field"
     - name: "my_field"
       enabled: false
       type: "http_url_field"

server/agent_config/custom_app.schema.yaml

@@ -501,6 +501,36 @@ $defs:
                   default: false
                   description@en: 'Whether to ignore case, default value: false, only effective when `Type` (`type`) is `String` (`string`).'
                   description@ch: 是否忽略大小写，默认值：false，仅当 `匹配类型`（`type`）为 `字符串`（`string`）时有效。
+                xml_attribute:
+                  type: object
+                  title@en: XML Attribute Match
+                  title@ch: XML 属性匹配
+                  description@en: |-
+                    Optional XML attribute matcher, only effective for `Payload XML Value` (`payload_xml_value`).
+
+                    Default values are empty for all fields, meaning attribute matching is skipped.
+                    When `Name` (`name`) and `Value` (`value`) are both non-empty, this matcher is enabled and combined with `Match` (`match`) using AND semantics.
+                  description@ch: |-
+                    可选的 XML 属性匹配，仅对 `XML 内容提取` (`payload_xml_value`) 生效。
+
+                    三个字段默认均为空，表示跳过属性匹配。
+                    仅当 `属性名`（`name`）和 `属性值`（`value`）都为非空时启用，并与 `匹配`（`match`）按 AND 关系同时生效。
+                  properties:
+                    name:
+                      type: string
+                      default: ""
+                      title@en: Attribute Name
+                      title@ch: 属性名
+                    value:
+                      type: string
+                      default: ""
+                      title@en: Attribute Value
+                      title@ch: 属性值
+                    ignore_case:
+                      type: boolean
+                      default: false
+                      title@en: Ignore Case
+                      title@ch: 忽略大小写
                 all_leaves:
                   type: boolean
                   title@en: All Leaves