refactor(k8s): keep the big-demo theme as real files under infra/keycloak/themes (refs #177)

The theme was inline text in a Helm template. It now lives next to the realms
and is seeded as rr-kc-theme by seed-configmaps.sh, like every other file
input, so it can be edited as a normal Keycloak theme. demo.otpAutofill now
only decides whether KC_SPI_THEME_DEFAULT is set (big.env skips values that
render empty); off, Keycloak keeps its stock theme.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

infra/helm/big-reference/templates/deployments.yaml

@@ -30,11 +30,6 @@ spec:
       annotations:
         checksum/portal-config: {{ include "big.keycloakUrl" $ | sha256sum }}
       {{- end }}
-      {{- /* Keycloak reads the theme at startup, so it restarts when the toggle flips. */}}
-      {{- if eq .configMap "kc-theme" }}
-      annotations:
-        checksum/otp-autofill: {{ $.Values.demo.otpAutofill | toString | sha256sum }}
-      {{- end }}
       {{- end }}
       labels:
 {{- include "big.labels" (dict "root" $ "name" $name) | nindent 8 }}