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).

helm/APP_NAME/templates/job-alembic-upgrade.yaml

@@ -0,0 +1,59 @@
+{{- if .Values.alembic.enabled }}
+# Job pre-upgrade que corre Alembic antes de rolar el Deployment.
+# - backoffLimit: 0  → si falla, NO reintenta; Helm aborta el upgrade.
+# - hook-delete-policy hook-succeeded → solo se borra al éxito; en fallo queda
+#   visible para `kubectl logs job/...` y diagnóstico.
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: {{ .Release.Name }}-alembic-{{ .Release.Revision }}
+  labels:
+    {{- include "app.labels" . | nindent 4 }}
+  annotations:
+    "helm.sh/hook": pre-upgrade,pre-install
+    "helm.sh/hook-weight": "0"
+    "helm.sh/hook-delete-policy": before-hook-creation,hook-succeeded
+spec:
+  backoffLimit: 0
+  ttlSecondsAfterFinished: 600
+  template:
+    metadata:
+      labels:
+        {{- include "app.labels" . | nindent 8 }}
+    spec:
+      restartPolicy: Never
+      serviceAccountName: {{ .Release.Name }}
+      imagePullSecrets:
+        - name: {{ .Values.image.pullSecret }}
+      securityContext:
+        runAsNonRoot: true
+        runAsUser: 1001
+      containers:
+        - name: alembic
+          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
+          command: {{ .Values.alembic.command | toJson }}
+          envFrom:
+            - secretRef:
+                name: {{ .Values.database.secretName }}
+          env:
+            # Si el Secret expone MIGRATION_DATABASE_URL, lo usa; si no, env.py
+            # cae a DATABASE_URL automáticamente (ver settings.migration_url).
+            - name: DATABASE_URL
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.database.secretName }}
+                  key: DATABASE_URL
+            - name: MIGRATION_DATABASE_URL
+              valueFrom:
+                secretKeyRef:
+                  name: {{ .Values.database.secretName }}
+                  key: MIGRATION_DATABASE_URL
+                  optional: true
+          resources:
+            {{- toYaml .Values.alembic.resources | nindent 12 }}
+          securityContext:
+            allowPrivilegeEscalation: false
+            readOnlyRootFilesystem: true
+            capabilities:
+              drop: ["ALL"]
+{{- end }}