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

zipline/Chart.yaml

@@ -15,7 +15,7 @@ type: application
 # This is the chart version. This version number should be incremented each time you make changes
 # to the chart and its templates, including the app version.
 # Versions are expected to follow Semantic Versioning (https://semver.org/)
-version: 4.0.0+up4.6.4
+version: 4.1.0+up4.6.4
 
 # This is the version number of the application being deployed. This version number should be
 # incremented each time you make changes to the application. Versions are not expected to