Add Kubernetes manifests for car.stinnesbeck.com

Namespace, InfluxDB 2.7.12 StatefulSet with PVC and a NetworkPolicy
that admits only the server, the server Deployment (non-root, read-only
root filesystem), a cert-manager Certificate from letsencrypt-prod and a
Traefik IngressRoute. Secrets are a template only. Nothing is applied;
k8s/README.md has the steps. Server version bumped to 1.1.0.

Validated offline with kustomize and kubeconform (including the
cert-manager and Traefik CRD schemas). The InfluxDB container was tested
locally as UID 1000 with no capabilities.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

k8s/kustomization.yaml

@@ -0,0 +1,12 @@
+# Render with `kustomize build k8s/` (or `kubectl kustomize k8s/`) and apply it yourself.
+# The Secrets are not included: create them from secrets.example.yaml first.
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+  - namespace.yaml
+  - influxdb.yaml
+  - server.yaml
+  - ingress.yaml
+images:
+  - name: git.stinnesbeck.com/nils/mg4-server
+    newTag: "1.1.0"