feat(archive): add tar and tar.gz converters

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

src/converters/archive.js

@@ -4,6 +4,7 @@ import path from 'node:path';
 import os from 'node:os';
 import AdmZip from 'adm-zip';
 import { ZipArchive } from 'archiver';
+import * as tar from 'tar';
 import { register } from './registry.js';
 
 const MAX_EXTRACTED_BYTES = 2 * 1024 * 1024 * 1024;
@@ -53,8 +54,24 @@ function createZip(srcDir, outputPath, quality) {
   });
 }
 
-const EXTRACTORS = { zip: extractZip };
-const CREATORS = { zip: createZip };
+async function extractTarLike(inputPath, destDir) {
+  // tar's extract auto-detects gzip compression from the file's magic bytes,
+  // so the same function handles both plain .tar and .tar.gz input.
+  await tar.extract({ file: inputPath, cwd: destDir });
+}
+
+async function createTar(srcDir, outputPath) {
+  const entries = await fs.readdir(srcDir);
+  await tar.create({ file: outputPath, cwd: srcDir }, entries);
+}
+
+async function createTarGz(srcDir, outputPath, quality) {
+  const entries = await fs.readdir(srcDir);
+  await tar.create({ file: outputPath, cwd: srcDir, gzip: { level: quality ?? 6 } }, entries);
+}
+
+const EXTRACTORS = { zip: extractZip, tar: extractTarLike, 'tar.gz': extractTarLike };
+const CREATORS = { zip: createZip, tar: createTar, 'tar.gz': createTarGz };
 
 async function convert(inputPath, outputPath, options, sourceFormat, targetFormat) {
   const { quality } = options ?? {};