feat(lasuite): migrate integration service to La Gaufre v2

Replace the inline gaufre.js/nginx.conf ConfigMap approach with a
purpose-built custom image (sunbeam/integration-service) that builds
the lagaufre.js v2 widget from the suitenumerique/integration source
and serves it via nginx.

Changes:
- Rewrite integration-deployment.yaml: custom image, v2 services.json
  format, only actually-deployed services (docs, meet, people)
- Add people-frontend nginx sub_filter overlay to rewrite the hardcoded
  production integration URL baked into the Next.js bundle at build time
- Register integration image in local overlay kustomization

overlays/local/patch-people-frontend-nginx.yaml

@@ -0,0 +1,20 @@
+# Patch: mount the nginx ConfigMap into people-frontend to rewrite the
+# hardcoded production integration URL at serve time.
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: people-frontend
+  namespace: lasuite
+spec:
+  template:
+    spec:
+      containers:
+        - name: desk
+          volumeMounts:
+            - name: nginx-conf
+              mountPath: /etc/nginx/conf.d/default.conf
+              subPath: default.conf
+      volumes:
+        - name: nginx-conf
+          configMap:
+            name: people-frontend-nginx-conf