docs(auth): two Pireon clients, production URLs and sign-in troubleshooting

- Registering clients: the authorization_code client is confidential and needs
  its secret; Pireon shows it once (rotate-secret if lost); containers must be
  recreated to read new environment variables.
- Production URLs (taskstream.pireon.dev, api.taskstream.pireon.dev) and their
  redirect URIs.
- "Si el login falla": each error seen while deploying (not configured,
  unauthorized_client, missing client_secret, invalid_client, redirect URI,
  expired code, wrong credentials, intermittent 404s) with cause and fix.
- READMEs mention both clients; Word/PDF regenerated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

docs/06-desarrollo.md

@@ -92,3 +92,4 @@ exporta facades, una página tampoco puede tocar un store ni despachar eventos p
 | La API no ve un evento nuevo al deserializar                                  | La clase del evento no tiene `@AutowiredEvent` o no se importa                                                            |
 | Un componente de `@pi/ui` lanza `Unable to find icon`                         | Falta registrar ese icono en `libs/web/shared/ui/src/lib/icons.ts`                                                        |
 | Tablas antiguas (`projects`, `issues`, `outbox`) en tu Postgres local         | Restos de una versión anterior sin event sourcing; `docker compose down -v` empieza de cero                               |
+| El login con Pireon falla (`unauthorized_client`, `client_secret`…)           | Configuración de los clientes OAuth: ver [Si el login falla](05-autenticacion.md#si-el-login-falla)                       |