feat: sincronizar scaffold completo del shape web-backend/python

Sincroniza el scaffold canónico desde templates/web-backend-python/ del
repo IDP. Reemplaza el placeholder mínimo previo (.gitea/workflows/ci.yaml,
README.md, .gitignore, catalog-info.yaml) por el scaffold completo
documentado en ADR-053 §3:

- code/ — FastAPI app con /health (db check), /metrics, /demo estático,
  middleware correlation_id, settings Pydantic, db.py con SQLAlchemy
- code/alembic/ — migración inicial vacía + env.py usando MIGRATION_DATABASE_URL
- code/tests/ — pytest + httpx TestClient (test_health, test_demo)
- helm/APP_NAME/ — chart con Deployment, Service, IngressRoute Traefik,
  NetworkPolicy, ServiceMonitor, Job alembic-upgrade como hook
  pre-upgrade,pre-install (backoffLimit: 0)
- coralware-shape.yaml — manifiesto v1alpha1 del contrato del shape
- claim-mariadb.yaml — AddonClaim declarativo (uso futuro ADR-052)
- catalog-info.yaml — entidad Backstage actualizada
- .gitea/workflows/APP_NAME-build.yaml — invoca reusable workflow ADR-038
  + job helm-deploy con KUBECONFIG_TENANT_B64

Placeholders __APP_NAME__, __TIER__, __TENANT_ID__, __TENANT_ID_NODASHES__
serán sustituidos server-side por repo-provisioner cuando materialice el
template para un tenant (pendiente — ADR-053 §11.5).

El openspec/ del golden path NO se sincroniza al repo Gitea (gobernanza
interna de Coralware).

Refs: ADR-052, ADR-053, poc-nexobms.md (PoC NexoBMS Demetrio).

code/app/main.py

@@ -0,0 +1,115 @@
+"""
+Aplicación FastAPI — entry point.
+
+Endpoints obligatorios del shape web-backend/python (ver coralware-shape.yaml):
+- /health   → liveness + readiness
+- /docs     → Swagger UI (auth opcional)
+- /demo     → frontend estático servido desde STATIC_DEMO_PATH
+- /metrics  → Prometheus
+
+Endpoints de dominio: agregar en app/routers/ y registrar en _register_routers().
+"""
+
+import logging
+import os
+
+from fastapi import Depends, FastAPI, HTTPException, Request, status
+from fastapi.responses import JSONResponse, Response
+from fastapi.staticfiles import StaticFiles
+from prometheus_client import CONTENT_TYPE_LATEST, generate_latest
+
+from app.db import db_alive
+from app.settings import settings
+
+logging.basicConfig(
+    level=getattr(logging, settings.LOG_LEVEL, logging.INFO),
+    format="%(asctime)s [%(levelname)s] [cid=%(correlation_id)s] %(message)s",
+    datefmt="%Y-%m-%dT%H:%M:%SZ",
+)
+
+
+class CorrelationIdFilter(logging.Filter):
+    def filter(self, record: logging.LogRecord) -> bool:
+        if not hasattr(record, "correlation_id"):
+            record.correlation_id = "-"
+        return True
+
+
+logging.getLogger().addFilter(CorrelationIdFilter())
+log = logging.getLogger("__APP_NAME__")
+
+
+def _require_auth_dep() -> None:
+    """
+    Dependency placeholder para /docs cuando OPENAPI_REQUIRE_AUTH=true.
+    Implementación real: validar JWT contra KEYCLOAK_ISSUER (ADR-029 R-004).
+    """
+    if not settings.OPENAPI_REQUIRE_AUTH:
+        return
+    raise HTTPException(
+        status_code=status.HTTP_401_UNAUTHORIZED,
+        detail="Auth requerido — implementar validación JWT contra Keycloak",
+    )
+
+
+def create_app() -> FastAPI:
+    app = FastAPI(
+        title="__APP_NAME__",
+        version="0.1.0",
+        dependencies=[Depends(_require_auth_dep)] if settings.OPENAPI_REQUIRE_AUTH else [],
+    )
+
+    @app.middleware("http")
+    async def correlation_id_middleware(request: Request, call_next):
+        cid = request.headers.get(settings.CORRELATION_ID_HEADER) or _generate_cid()
+        request.state.correlation_id = cid
+        response = await call_next(request)
+        response.headers[settings.CORRELATION_ID_HEADER] = cid
+        return response
+
+    @app.get("/health", tags=["platform"])
+    async def health() -> JSONResponse:
+        db_status = "up" if db_alive() else "down"
+        code = 200 if db_status == "up" else 503
+        return JSONResponse(
+            status_code=code,
+            content={"status": "ok" if code == 200 else "degraded", "db": db_status},
+        )
+
+    @app.get("/metrics", tags=["platform"])
+    async def metrics() -> Response:
+        return Response(content=generate_latest(), media_type=CONTENT_TYPE_LATEST)
+
+    if os.path.isdir(settings.STATIC_DEMO_PATH):
+        app.mount(
+            "/demo",
+            StaticFiles(directory=settings.STATIC_DEMO_PATH, html=True),
+            name="demo",
+        )
+    else:
+        log.warning(
+            "STATIC_DEMO_PATH=%s no existe — endpoint /demo no será servido",
+            settings.STATIC_DEMO_PATH,
+        )
+
+    _register_routers(app)
+    return app
+
+
+def _generate_cid() -> str:
+    """Genera correlation_id si el cliente no envió uno."""
+    import time
+    import uuid
+
+    return f"__APP_NAME__-{int(time.time() * 1000)}-{uuid.uuid4().hex[:8]}"
+
+
+def _register_routers(app: FastAPI) -> None:
+    """
+    Registra los routers de dominio.
+    Agrega aquí los include_router(...) conforme tu app crezca.
+    """
+    pass
+
+
+app = create_app()