Conventions batch 2: flexible ingress standard, configurable probes

Establish the flexible ingress standard from #32 in template-chart and
document it in README/CLAUDE.md: ingress.domain and ingress.clusterIssuer
stay required, new ingress.className value (default nginx) replaces the
hardcoded ingressClassName, new optional ingress.annotations are merged
with the cert-manager cluster-issuer annotation, TLS secret name
unchanged (tls-<release>-<chart>-ingress).

Apply the standard to cyberchef and patchmon (the two charts without an
own batch-3 major PR) and make the patchmon probes values-configurable
(server + guacd, rendered through tpl so the default Host header keeps
following ingress.domain). Defaults render semantically identical to the
previous hardcoded output.

cyberchef 5.0.1 -> 5.1.0, patchmon 5.0.1 -> 5.1.0 (minor, additive).

template-chart/values.yaml

@@ -84,3 +84,7 @@ ingress:
   enabled: true
   clusterIssuer: null
   domain: null
+  className: nginx
+  # Extra annotations for the Ingress; merged with the cert-manager
+  # cluster-issuer annotation the chart always sets.
+  annotations: {}