fix: 保留文本块原始空格并优化块合并逻辑

修复kb_utils.py中文本块内容被意外去除空格的问题
优化chunkUtils.js中块合并逻辑，当无重叠时添加换行符

src/knowledge/utils/kb_utils.py

@@ -90,7 +90,7 @@ def split_text_into_chunks(text: str, file_id: str, filename: str, params: dict
             chunks.append(
                 {
                     "id": f"{file_id}_chunk_{chunk_index}",
-                    "content": chunk_content.strip(),
+                    "content": chunk_content, # .strip(),
                     "file_id": file_id,
                     "filename": filename,
                     "chunk_index": chunk_index,

web/src/utils/chunkUtils.js

@@ -16,7 +16,7 @@ export function findOverlap(str1, str2) {
   let overlap = '';
 
   // 从最长可能的重叠开始检查
-  for (let i = maxOverlap; i > 0; i--) {
+  for (let i = maxOverlap; i > 10; i--) {
     const endStr1 = str1.slice(-i);
     const startStr2 = str2.slice(0, i);
 
@@ -63,7 +63,11 @@ export function mergeChunks(chunks) {
 
       if (newContent.length > 0) {
         const startOffset = currentContent.length;
-        currentContent += newContent;
+        if (overlap.length > 0) {
+          currentContent += newContent;
+        } else {
+          currentContent += `\n${newContent}`;
+        }
         merged.push({
           ...chunk,
           startOffset,