Add per-workload replicas values and a chart-global scaleDown flag

Every Deployment/StatefulSet now takes its replica count from a replicas
value (default 1, explicit 0 allowed) via a new per-chart <chart>.replicas
helper; the helper uses a kindIs "invalid" nil check so an explicit 0 is
not swallowed by Helm's default function. A chart-global scaleDown flag
(default false) takes precedence: it renders every workload with
replicas: 0 and suspends the paperless-ngx consume CronJob, stopping the
app without uninstalling it (PVCs, Secrets, Services and Ingress remain).

Defaults leave the rendered manifests byte-identical to main, so all
published charts get a minor version bump; the template-chart carries the
reference helper implementation and stays unversioned.

Fixes #25

urlaubsverwaltung/values.yaml

@@ -1,3 +1,9 @@
+# Scale the whole chart down without uninstalling it: scaleDown: true renders
+# every Deployment/StatefulSet with replicas: 0 (and suspends CronJobs) and
+# takes precedence over any per-workload replicas value. PVCs, Secrets and
+# Services stay in place; scaleDown: false brings the workloads back up.
+scaleDown: false
+
 secrets:
   databaseSecretRef: null
   oidcSecretRef: null
@@ -7,6 +13,9 @@ ingress:
   domain: null
 
 urlaubsverwaltung:
+  # Replica count for this workload; 0 is allowed and scales it down.
+  # The chart-global scaleDown flag takes precedence.
+  replicas: 1
   # The official image is built with Cloud Native Buildpacks and runs as the
   # non-root cnb user (uid 1002, gid 1001). /tmp is a writable emptyDir for
   # the JVM's temp/work files.
@@ -30,4 +39,4 @@ urlaubsverwaltung:
     requests:
       cpu: 0.1
       memory: 768Mi
-      ephemeralStorage: 10Mi
+      ephemeralStorage: 10Mi