Revert "feat: 添加 GBK 编码自动检测支持，文件读写工具透明处理非 UTF-8 文件"

This reverts commit 0ce8f7a1cb.

packages/builtin-tools/src/tools/FileEditTool/FileEditTool.ts

@@ -34,11 +34,6 @@ import {
   type LineEndingType,
   readFileSyncWithMetadata,
 } from 'src/utils/fileRead.js'
-import {
-  detectEncoding,
-  decodeBuffer,
-  type FileEncoding,
-} from 'src/utils/encoding.js'
 import { formatFileSize } from 'src/utils/format.js'
 import { getFsImplementation } from 'src/utils/fsOperations.js'
 import { fetchSingleFileGitDiff, type ToolUseDiff } from 'src/utils/gitDiff.js'
@@ -207,8 +202,13 @@ export const FileEditTool = buildTool({
     let fileContent: string | null
     try {
       const fileBuffer = await fs.readFileBytes(fullFilePath)
-      const encoding: FileEncoding = detectEncoding(fileBuffer)
-      fileContent = decodeBuffer(fileBuffer, encoding).replaceAll('\r\n', '\n')
+      const encoding: BufferEncoding =
+        fileBuffer.length >= 2 &&
+        fileBuffer[0] === 0xff &&
+        fileBuffer[1] === 0xfe
+          ? 'utf16le'
+          : 'utf8'
+      fileContent = fileBuffer.toString(encoding).replaceAll('\r\n', '\n')
     } catch (e) {
       if (isENOENT(e)) {
         fileContent = null
@@ -584,7 +584,7 @@ export const FileEditTool = buildTool({
 function readFileForEdit(absoluteFilePath: string): {
   content: string
   fileExists: boolean
-  encoding: FileEncoding
+  encoding: BufferEncoding
   lineEndings: LineEndingType
 } {
   try {