feat: import job runner in-memory

- Añade ImportRunner en memoria con concurrencia configurable
- Tests TDD para enqueue, concurrencia y comportamiento tras stop
- Actualiza /api/import/scan para encolar jobs y registrar errores
- Ajusta tsconfig.json para incluir tests en comprobaciones de tipo

backend/src/services/checksumService.ts

@@ -0,0 +1,62 @@
+import fs from 'fs';
+import { createHash } from 'crypto';
+
+function makeCRCTable(): Uint32Array {
+  const table = new Uint32Array(256);
+  for (let n = 0; n < 256; n++) {
+    let c = n;
+    for (let k = 0; k < 8; k++) {
+      if (c & 1) c = 0xedb88320 ^ (c >>> 1);
+      else c = c >>> 1;
+    }
+    table[n] = c >>> 0;
+  }
+  return table;
+}
+
+const CRC_TABLE = makeCRCTable();
+
+function updateCrc(crc: number, buf: Buffer): number {
+  let c = crc >>> 0;
+  for (let i = 0; i < buf.length; i++) {
+    c = (CRC_TABLE[(c ^ buf[i]) & 0xff] ^ (c >>> 8)) >>> 0;
+  }
+  return c >>> 0;
+}
+
+export async function computeHashes(filePath: string): Promise<{
+  size: number;
+  md5: string;
+  sha1: string;
+  crc32: string;
+}> {
+  return new Promise((resolve, reject) => {
+    const md5 = createHash('md5');
+    const sha1 = createHash('sha1');
+
+    let size = 0;
+    let crc = 0xffffffff >>> 0;
+
+    const rs = fs.createReadStream(filePath);
+
+    rs.on('error', (err) => reject(err));
+
+    rs.on('data', (chunk: Buffer) => {
+      md5.update(chunk);
+      sha1.update(chunk);
+      size += chunk.length;
+      crc = updateCrc(crc, chunk);
+    });
+
+    rs.on('end', () => {
+      const md5sum = md5.digest('hex');
+      const sha1sum = sha1.digest('hex');
+      const final = (crc ^ 0xffffffff) >>> 0;
+      const crcHex = final.toString(16).padStart(8, '0').toLowerCase();
+
+      resolve({ size, md5: md5sum, sha1: sha1sum, crc32: crcHex });
+    });
+  });
+}
+
+export default computeHashes;

backend/src/services/datVerifier.ts

@@ -0,0 +1,11 @@
+export function parseDat(_xml: string): any {
+  // Stub: el parseo completo no se implementa en esta fase.
+  return {};
+}
+
+export async function verifyRomAgainstDat(_romMeta: any, _parsedDat: any): Promise<any> {
+  // Stub: verificación mínima para que los tests de integración puedan ser saltados.
+  return {};
+}
+
+export default { parseDat, verifyRomAgainstDat };

backend/src/services/fsScanner.ts

@@ -0,0 +1,42 @@
+import path from 'path';
+import { promises as fsPromises } from 'fs';
+import { detectFormat } from '../lib/fileTypeDetector';
+
+export async function scanDirectory(dirPath: string): Promise<any[]> {
+  const results: any[] = [];
+
+  async function walk(dir: string) {
+    const entries = await fsPromises.readdir(dir, { withFileTypes: true });
+
+    for (const entry of entries) {
+      if (entry.name.startsWith('.')) continue; // ignore dotfiles
+
+      const full = path.join(dir, entry.name);
+
+      if (entry.isDirectory()) {
+        await walk(full);
+        continue;
+      }
+
+      if (entry.isFile()) {
+        const stat = await fsPromises.stat(full);
+        const format = detectFormat(entry.name);
+        const isArchive = ['zip', '7z', 'chd'].includes(format);
+
+        results.push({
+          path: full,
+          filename: entry.name,
+          name: entry.name,
+          size: stat.size,
+          format,
+          isArchive,
+        });
+      }
+    }
+  }
+
+  await walk(dirPath);
+  return results;
+}
+
+export default scanDirectory;