feat: 完善文档分块参数配置

- 支持自定义正则匹配内容保留开关及配置持久化

- 约束分块重叠长度始终小于分块长度

- 补充中英文交互文案

easyflow-ui-admin/app/src/locales/langs/zh-CN/documentCollection.json

@@ -159,6 +159,9 @@
     "chunkSize": "分段长度",
     "overlapSize": "分段重叠",
     "regex": "正则表达式",
+    "regexMatchHandling": "匹配内容处理",
+    "retainRegexMatch": "保留到下一分块",
+    "discardRegexMatch": "不保留",
     "document": "文档",
     "simpleDocumentSplitter": "简单文档分割器",
     "simpleTokenizeSplitter": "简单分词器",