calibre-web-automated: strict schema, ingress gate and null-safe hardening

Three changes, all about values that do not do what they promise:

1. values.schema.json (#68): additionalProperties: false on every
   chart-owned object level.

2. Ingress gate (#93): the Ingress template is wrapped in
   {{- if .Values.ingress.enabled }} and the key is added to values.yaml
   with default true, so behaviour is unchanged.

   The domain checkpoint from rallly ran over values.yaml and templates
   and came back empty here: ingress.domain is read nowhere but in the
   Ingress template. Unlike rallly, zipline, voucher-vault and outline,
   this gate therefore frees both domain and clusterIssuer, and no extra
   required() is needed.

3. Null-safety for hardening, probes and resources (#99).

   This chart's hardening is a documented deviation from the repo
   standard, and the fallbacks reproduce it exactly instead of restoring
   the standard: no runAs* values (s6-overlay boots as root and drops to
   PUID/PGID 1000), readOnlyRootFilesystem stays false (read-only mode
   disables the PUID/PGID remapping, silently moving the runtime uid from
   1000 to 911 and breaking existing volume data), and capabilities.add
   keeps its six entries that the s6 init and supervision need. A
   "cleaned up" standard default here would not be tidier, it would be an
   outage.

cwa.storage stays deliberately not null-safe: an erased value yields an
invalid PVC, which is the loud class #99 excludes.

Rendering with normal values is byte-identical to 4.0.0.

calibre-web-automated/Chart.yaml

@@ -5,7 +5,7 @@ name: calibre-web-automated
 description: A Helm chart to deploy calibere-web-automated
 icon: https://raw.githubusercontent.com/crocodilestick/Calibre-Web-Automated/main/README_images/cwa-logo-round-dark.png
 
-version: 4.0.0+upv4.0.6
+version: 5.0.0+upv4.0.6
 appVersion: v4.0.6
 
 maintainers: