feat(captura): fold recibo OCR into Captura as an automatic mode

Scanning a stack of bills and keying them in are the same daily job, ending
in the same ledger path, so OCR intake becomes a mode of the capture screen
instead of a second menu entry:

- components/Captura.tsx holds the mode switch; the manual check form moves
  verbatim to components/ManualCheckCapture.tsx and the OCR intake to
  components/StatementIntake.tsx.
- /estado-cuenta/lote opens on manual, /recibos on automatic — both render
  Captura, so batch-review links and old bookmarks still land right.
- Nav drops "Recibos (OCR)"; "Captura" covers both, with a NavLink.aliases
  field so /recibos still highlights it.

Also fixes the "El almacenamiento de documentos no está configurado" failure
staff hit on upload. Uploading with no object storage configured used to
succeed, then die on the first put minutes later, leaving a FAILED batch
whose only explanation was that string. createBatch now refuses up front,
GET /statements/status reports storageAvailable alongside ocrAvailable, and
the intake tab explains the situation instead of offering an upload that
cannot work. S3_* documented in .env.example (deploy stacks already set it).

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

apps/api/src/storage/storage.service.ts

@@ -73,6 +73,16 @@ export class StorageService implements OnModuleInit {
     }
   }
 
+  /**
+   * Whether the deployment has object storage at all. Callers use this to
+   * refuse work up front instead of failing halfway through — a recibo batch
+   * that dies on its first `put` leaves a FAILED batch and no explanation the
+   * office can act on.
+   */
+  get available(): boolean {
+    return this.client !== null;
+  }
+
   private require(): S3Client {
     if (!this.client) {
       throw new ServiceUnavailableException(