fix: write the runtime config in the web image too

The Kubernetes deployment runs the split go-guess-web image, which is a plain
nginx serving static files and never ran an entrypoint. The theme service origin
is therefore never written into runtime-config.js there, so the page would always
read the empty default and theming would be silently inert in the cluster while
working in local runs. The combined root image already did this; the split one
now does too.

The script lives beside the frontend Dockerfile because that image's build
context is ./frontend, which cannot see docker/.

The chart passes THEME_BASE_URL to the web container rather than the API: it is
read by the browser, not by the service. It stays absent when unset, so a
deployment with no theme service renders exactly as before.

deploy/helm/go-guess/templates/web-deployment.yaml

@@ -39,6 +39,14 @@ spec:
           imagePullPolicy: {{ .Values.web.image.pullPolicy }}
           securityContext:
             {{- toYaml .Values.web.securityContext | nindent 12 }}
+          env:
+            {{- with .Values.web.themeBaseUrl }}
+            # Read by the browser, not the API, so it goes to the web container:
+            # the entrypoint writes it into runtime-config.js on start. Empty keeps
+            # the application on its own styling.
+            - name: THEME_BASE_URL
+              value: {{ . | quote }}
+            {{- end }}
           ports:
             - name: http
               containerPort: 80

deploy/helm/go-guess/values.yaml

@@ -78,8 +78,13 @@ web:
   replicaCount: 2
   image:
     repository: batty1039.startdedicated.net:5000/go-guess-web
-    tag: "0.0.1"
+    tag: "0.1.0"
     pullPolicy: IfNotPresent
+  # Origin of the go-bananas runtime supplying the shared styling contract, for
+  # example https://bananas-dev.urpi.be. Empty keeps this application's own
+  # styles. The theme service must also allow this application's origin, or the
+  # browser refuses to load the controls from it.
+  themeBaseUrl: ""
   service:
     type: ClusterIP
     port: 80