feat(adapter-wp): saxes 流式 WXR 解析器

parseWxrStream(readable, {limits, now}) → AsyncGenerator<WxrEvent>：
逐 chunk 喂入 saxes（^6.0.0，ISC；计划所写 ^0.9 不存在于版本历史），
item/term 按文档序交错产出；任一时刻只持有当前聚合状态 + 单 chunk 内
待 yield 队列，绝不收集已产出 item 列表（峰值内存与文件大小解耦）。

- 字段：postId(数值解析)/postType/status/postName/link/title/
  contentEncoded/excerptEncoded/postDate/postModified/attachmentUrl/
  creator + metas{key,value}[] + categories{domain,nicename,value}[] +
  rawLocation(wxr://item/<n>、wxr://term/<n>)
- 错误体系照 PhpError 先例：WxrError 基类；WxrParseError 带 saxes
  行列位置（error 事件同步抛出时捕获）；WxrLimitError 按 kind 区分
- 限额：bytes/items/terms/depth/cdata/fieldLength（先检查后追加，
  超限内容永不入缓冲）/metaPerItem/time（可注入时钟）——超限即抛，
  不静默截断
- 实体防线（测试钉死）：saxes 实体表固定为五预定义 + 数字引用，
  DOCTYPE 内部/SYSTEM 实体不注册——引用即 WxrParseError，替换文本
  不进产出；纯字符串解析，全程无网络 I/O
- 跨 chunk 喂入（7 字节/块）与单 chunk 产出一致（StringDecoder 处理
  多字节边界）；畸形 XML（提前闭合/截断）→ WxrParseError 带行列

130 测试全绿（新增 22）。

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

pnpm-lock.yaml

@@ -66,6 +66,9 @@ importers:
       '@sf/contracts':
         specifier: workspace:*
         version: link:../contracts
+      saxes:
+        specifier: ^6.0.0
+        version: 6.0.0
 
   packages/contracts: {}
 
@@ -1513,6 +1516,10 @@ packages:
   rxjs@7.8.2:
     resolution: {integrity: sha512-dhKf903U/PQZY6boNNtAGdWbG85WAbjT/1xYoZIC7FAY0yWapOBQVsVrDl58W86//e1VpMNBtRV4MaXfdMySFA==}
 
+  saxes@6.0.0:
+    resolution: {integrity: sha512-xAg7SOnEhrm5zI3puOOKyy1OMcMlIJZYNJY7xLBwSze0UjhPLnWfj2GF2EpT0jmzaJKIWKHLsaSSajf35bcYnA==}
+    engines: {node: '>=v12.22.7'}
+
   semver@7.8.5:
     resolution: {integrity: sha512-Y7/KDsb8LjooZpwaqGyulO6DQlksgCncchHGk+sZIY4SBvUocMBEFH5Ur1fI4dV+Jvl0w6cjvucaIi40puRioA==}
     engines: {node: '>=10'}
@@ -1712,6 +1719,9 @@ packages:
     resolution: {integrity: sha512-BN22B5eaMMI9UMtjrGd5g5eCYPpCPDUy0FJXbYsaT5zYxjFOckS53SQDE3pWkVoWpHXVb3BrYcEN4Twa55B5cA==}
     engines: {node: '>=0.10.0'}
 
+  xmlchars@2.2.0:
+    resolution: {integrity: sha512-JZnDKK8B0RCDw84FNdDAIpZK+JuJw+s7Lz8nksI7SIuU3UXJJslUthsi+uWBUYOwPFwW7W7PRLRfUKpxjtjFCw==}
+
   yocto-queue@0.1.0:
     resolution: {integrity: sha512-rVksvsnNCdJ/ohGc6xgPwyN8eheCxsiLM8mxuE/t/mOVqJewPuO1miLpTHQiRgTKCLexL4MeAFVagts7HmNZ2Q==}
     engines: {node: '>=10'}
@@ -2843,6 +2853,10 @@ snapshots:
     dependencies:
       tslib: 2.8.1
 
+  saxes@6.0.0:
+    dependencies:
+      xmlchars: 2.2.0
+
   semver@7.8.5: {}
 
   shebang-command@2.0.0:
@@ -3020,4 +3034,6 @@ snapshots:
 
   word-wrap@1.2.5: {}
 
+  xmlchars@2.2.0: {}
+
   yocto-queue@0.1.0: {}