feat: expose archive entries in fsScanner

- Añade `scanDirectory` support para listar entradas internas de ZIP/7z
- Añade test unitario que mockea `archiveReader.listArchiveEntries`
- Añade límite configurable `ARCHIVE_MAX_ENTRIES` y comprobación básica de seguridad

backend/tests/services/fsScanner.archiveEntries.spec.ts

@@ -0,0 +1,35 @@
+import path from 'path';
+import os from 'os';
+import { promises as fs } from 'fs';
+import { afterEach, it, expect, vi } from 'vitest';
+
+vi.mock('../../src/services/archiveReader', () => ({ listArchiveEntries: vi.fn() }));
+
+import scanDirectory from '../../src/services/fsScanner';
+import { listArchiveEntries } from '../../src/services/archiveReader';
+
+afterEach(() => vi.restoreAllMocks());
+
+it('expone entradas internas de archivos como items virtuales', async () => {
+  const tmpDir = await fs.mkdtemp(path.join(os.tmpdir(), 'fsScanner-test-'));
+  const collectionFile = path.join(tmpDir, 'collection.zip');
+  await fs.writeFile(collectionFile, '');
+
+  (listArchiveEntries as unknown as vi.Mock).mockResolvedValue([
+    { name: 'inner/rom1.bin', size: 1234 },
+  ]);
+
+  const results = await scanDirectory(tmpDir);
+
+  const expectedPath = `${collectionFile}::inner/rom1.bin`;
+  const found = results.find((r: any) => r.path === expectedPath);
+
+  expect(found).toBeDefined();
+  expect(found.isArchiveEntry).toBe(true);
+  expect(found.containerPath).toBe(collectionFile);
+  expect(found.entryPath).toBe('inner/rom1.bin');
+  expect(found.filename).toBe('rom1.bin');
+  expect(found.format).toBe('bin');
+
+  await fs.rm(tmpDir, { recursive: true, force: true });
+});