feat: stream hashing and archive-entry import support

- Añade `computeHashesFromStream` para hashing desde streams
- Adapta `importDirectory` para procesar entradas internas usando `streamArchiveEntry`
- Añade tests unitarios para hashing por stream e import de entradas de archive

backend/tests/services/checksumService.stream.spec.ts

@@ -0,0 +1,24 @@
+import { describe, it, expect } from 'vitest';
+import { Readable } from 'stream';
+import fs from 'fs/promises';
+import path from 'path';
+
+import { computeHashes, computeHashesFromStream } from '../../src/services/checksumService';
+
+describe('services/checksumService (stream)', () => {
+  it('computeHashesFromStream produces same result as computeHashes(file)', async () => {
+    const data = Buffer.from('quasar-stream-test');
+    const tmpDir = await fs.mkdtemp(path.join(process.cwd(), 'tmp-checksum-'));
+    const tmpFile = path.join(tmpDir, 'test.bin');
+    await fs.writeFile(tmpFile, data);
+
+    const expected = await computeHashes(tmpFile);
+
+    const rs = Readable.from([data]);
+    const actual = await computeHashesFromStream(rs as any);
+
+    expect(actual).toEqual(expected);
+
+    await fs.rm(tmpDir, { recursive: true, force: true });
+  });
+});