refactor: use existing strip-bom package instead of custom bomUtils

- Remove src/utils/bomUtils.ts and its test file
- Update imports in extract-text.ts to use strip-bom package
- Update imports in read-lines.ts to use strip-bom package
- Keep the empty file detection logic in readFileTool.ts unchanged

This eliminates code duplication by using the existing strip-bom package
that is already used in DiffViewProvider.ts and CustomModesManager.ts.

Author: roomote

src/integrations/misc/extract-text.ts

@@ -5,7 +5,7 @@ import mammoth from "mammoth"
 import fs from "fs/promises"
 import { isBinaryFile } from "isbinaryfile"
 import { extractTextFromXLSX } from "./extract-text-from-xlsx"
-import { stripBOM } from "../../utils/bomUtils"
+import stripBom from "strip-bom"
 
 async function extractTextFromPDF(filePath: string): Promise<string> {
 	const dataBuffer = await fs.readFile(filePath)
@@ -70,7 +70,7 @@ export async function extractTextFromFile(filePath: string): Promise<string> {
 	if (!isBinary) {
 		const content = await fs.readFile(filePath, "utf8")
 		// Strip BOM if present before adding line numbers
-		return addLineNumbers(stripBOM(content))
+		return addLineNumbers(stripBom(content))
 	} else {
 		throw new Error(`Cannot read text for file type: ${fileExtension}`)
 	}

src/integrations/misc/read-lines.ts

@@ -7,7 +7,7 @@
  * Now you can read a range of lines from a file
  */
 import { createReadStream } from "fs"
-import { stripBOM } from "../../utils/bomUtils"
+import stripBom from "strip-bom"
 
 const outOfRangeError = (filepath: string, n: number) => {
 	return new RangeError(`Line with index ${n} does not exist in '${filepath}'. Note that line indexing is zero-based`)
@@ -70,7 +70,7 @@ export function readLines(filepath: string, endLine?: number, startLine?: number
 
 			// Strip BOM from the first chunk if present
 			if (isFirstChunk) {
-				chunkStr = stripBOM(chunkStr)
+				chunkStr = stripBom(chunkStr)
 				isFirstChunk = false
 			}