feat(archive): add rar extraction support

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

test/converters/archive.test.js

@@ -228,3 +228,32 @@ describe('archive converters — 7z and tar.7z', () => {
     20000
   );
 });
+
+describe('archive converters — rar (extraction only)', () => {
+  it('lists rar as a source with the other 6 archive formats as targets, and never lists rar as a target for anything', () => {
+    const targets = listTargetFormats('rar');
+    expect(targets.sort()).toEqual(['7z', 'tar', 'tar.7z', 'tar.bz2', 'tar.gz', 'zip'].sort());
+    expect(listTargetFormats('zip')).not.toContain('rar');
+  });
+
+  it('converts the sample.rar fixture to zip', async () => {
+    const rarPath = path.join(import.meta.dirname, '..', 'fixtures', 'sample.rar');
+    const outputPath = path.join(tmpDir, 'from-rar.zip');
+    const entry = resolve('rar', 'zip');
+
+    await entry.convert(rarPath, outputPath);
+
+    const outZip = new AdmZip(outputPath);
+    expect(outZip.getEntries().length).toBeGreaterThan(0);
+  });
+});
+
+describe('archive converters — full registration matrix', () => {
+  it('registers all 42 source/target pairs (7 sources x 6 targets)', () => {
+    const sources = ['zip', 'tar', 'tar.gz', 'tar.bz2', '7z', 'tar.7z', 'rar'];
+    const targets = ['zip', 'tar', 'tar.gz', 'tar.bz2', '7z', 'tar.7z'];
+    for (const source of sources) {
+      expect(listTargetFormats(source).sort()).toEqual(targets.sort());
+    }
+  });
+});

test/fixtures/RAR_ATTRIBUTION.md

@@ -0,0 +1,9 @@
+# RAR fixture attribution
+
+`sample.rar` is a byte-identical copy of `testFiles/FolderTest.rar` from the
+[YuJianrong/node-unrar.js](https://github.com/YuJianrong/node-unrar.js)
+repository (MIT-licensed), used there for that project's own extraction
+tests. Reused here because there is no way to create a `.rar` fixture from
+this codebase — the `unrar` library's license bars any tool (including this
+project's own converters) from writing the RAR format, so RAR support is
+extraction-only everywhere, including in test fixtures.