feat: plantilla base workspace SaaS

Convierte el repositorio de Anexo76 en una plantilla limpia y reutilizable
para nuevos proyectos del ecosistema Workspace de Aduanasoft.

Cambios principales:
- Elimina módulos específicos de Anexo76: a76, a24, sitar, public
- Agrega módulo example/ con patrón CRUD de referencia (models/dto/service/routes)
- Limpia migraciones Alembic: solo quedan las 6 de core (users, tenants, permissions)
- Reemplaza todas las rutas del dashboard con stubs genéricos
- Elimina lógica de negocio aduanera: shortcuts, CSV imports, permisos, catálogos
- Simplifica variables de entorno: una sola WORKSPACE_URL deriva Hub y Keycloak
- Agrega scripts/auth-mode.sh para alternar entre auth local y workspace
- Configura docker-compose con nombres genéricos (app-*)
- Corrige flujo SSO: elimina system-gate SCAF/SCAII que bloqueaba el login
- Modo DEV_LOCAL_AUTH para desarrollo sin Keycloak ni Hub

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/api/v1/modules/example/routes.py

@@ -0,0 +1,65 @@
+from fastapi import APIRouter, Depends, Query, status
+from sqlalchemy.orm import Session
+
+from core.database import get_core_db
+from core.security import get_current_user
+
+from .dto import ItemCreate, ItemResponse, ItemUpdate
+from . import service
+
+router = APIRouter()
+
+
+@router.get("/items", response_model=list[ItemResponse])
+def list_items(
+    company_id: int = Query(..., description="Company ID"),
+    current_user: dict = Depends(get_current_user),
+    db: Session = Depends(get_core_db),
+):
+    tenant_id = current_user["tenant_id"]
+    return service.get_items(db, tenant_id, company_id)
+
+
+@router.get("/items/{item_id}", response_model=ItemResponse)
+def get_item(
+    item_id: int,
+    company_id: int = Query(..., description="Company ID"),
+    current_user: dict = Depends(get_current_user),
+    db: Session = Depends(get_core_db),
+):
+    tenant_id = current_user["tenant_id"]
+    return service.get_item(db, item_id, tenant_id, company_id)
+
+
+@router.post("/items", response_model=ItemResponse, status_code=status.HTTP_201_CREATED)
+def create_item(
+    payload: ItemCreate,
+    company_id: int = Query(..., description="Company ID"),
+    current_user: dict = Depends(get_current_user),
+    db: Session = Depends(get_core_db),
+):
+    tenant_id = current_user["tenant_id"]
+    return service.create_item(db, payload, tenant_id, company_id)
+
+
+@router.patch("/items/{item_id}", response_model=ItemResponse)
+def update_item(
+    item_id: int,
+    payload: ItemUpdate,
+    company_id: int = Query(..., description="Company ID"),
+    current_user: dict = Depends(get_current_user),
+    db: Session = Depends(get_core_db),
+):
+    tenant_id = current_user["tenant_id"]
+    return service.update_item(db, item_id, payload, tenant_id, company_id)
+
+
+@router.delete("/items/{item_id}", status_code=status.HTTP_204_NO_CONTENT)
+def delete_item(
+    item_id: int,
+    company_id: int = Query(..., description="Company ID"),
+    current_user: dict = Depends(get_current_user),
+    db: Session = Depends(get_core_db),
+):
+    tenant_id = current_user["tenant_id"]
+    service.delete_item(db, item_id, tenant_id, company_id)