Add coulomb-social Helm chart and deploy targets

Chart mirrors vergabe-teilnahme Django probe/secret pattern. Non-secret
values pin KeyCape OIDC and user-engine URL; env Secret holds secrets.
Makefile: dry-run, deploy, ingress, status, logs.

manifests/coulomb-social-ingress.yaml

@@ -0,0 +1,26 @@
+# Ingress for coulomb.social (apply after first chart deploy).
+# Requires cert-manager ClusterIssuer and DNS for coulomb.social → cluster.
+apiVersion: networking.k8s.io/v1
+kind: Ingress
+metadata:
+  name: coulomb-social
+  namespace: coulomb-social
+  annotations:
+    cert-manager.io/cluster-issuer: letsencrypt-prod
+    traefik.ingress.kubernetes.io/router.entrypoints: websecure
+spec:
+  ingressClassName: traefik
+  tls:
+    - hosts: [coulomb.social]
+      secretName: coulomb-social-tls
+  rules:
+    - host: coulomb.social
+      http:
+        paths:
+          - path: /
+            pathType: Prefix
+            backend:
+              service:
+                name: coulomb-social
+                port:
+                  number: 80