docs: POC-katselmus — git-pages retention, ADRt, dokumenttipäivitykset

- ADR 0004: commit-status-periaate (natiivi riittää, API vain custom-linkkiin)
- ADR 0005: provider & consumer -malli (ci-engine.yml lukittu rajapinta)
- docs/design-rationale: uusi periaate 1 "Hyödynnä natiivia",
  periaate 2 korjattu (API vain tarvittaessa),
  periaate 6 (MinIO→git-pages), teknologiavalinnat poistettu
- docs/config-model: isContainerBuild→isArtifactBuild, Docker-labelit poistettu
- docs/ai-context: monorepo-kuvaus (git-pages oma kokonaisuus, ohut rajapinta)
- docs/architecture, tech-stack, report-hosting, shared-scripts, workflows:
  MinIO→git-pages, provider agnostinen build-ekosysteemeille
- docs/adr/: ADRt siirretty decisions/→adr/
- git-pages/docs: retention-osiot päivitetty CronJob→sidecar+HTTP API,
  URL-kaava korjattu (reports/{sha8}/)
- git-pages/docs/implementation-notes: uusi (storage v2, Host-header,
  whiteout, .init, PATCH+directoryt)
- git-pages/templates/init-job.yaml: post-install init (.index)
- scripts/publish-git-pages.sh: PUT-fallback poistettu (init hoitaa),
  palauttaa BASE URL ilman index.html

git-pages/templates/init-job.yaml

@@ -0,0 +1,48 @@
+{{- if .Values.initJob.enabled }}
+apiVersion: batch/v1
+kind: Job
+metadata:
+  name: {{ include "git-pages.fullname" . }}-init
+  labels:
+    {{- include "git-pages.componentLabels" . | nindent 4 }}
+  annotations:
+    "helm.sh/hook": post-install, post-upgrade
+    "helm.sh/hook-delete-policy": hook-succeeded,before-hook-creation
+spec:
+  backoffLimit: 5
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: {{ include "git-pages.name" . }}-init
+        app.kubernetes.io/instance: {{ .Release.Name }}
+    spec:
+      restartPolicy: Never
+      containers:
+        - name: init
+          image: "{{ .Values.initJob.image.repository }}:{{ .Values.initJob.image.tag }}"
+          imagePullPolicy: {{ .Values.initJob.image.pullPolicy }}
+          command:
+            - bash
+            - -c
+            - |
+              set -euo pipefail
+              apt-get update -qq && apt-get install -y -qq curl tar >/dev/null
+              echo "Init: waiting for git-pages..."
+              until curl -sf \
+                -H "Host: {{ .Values.ingress.host }}" \
+                -o /dev/null "http://git-pages:3000/.git-pages/health"
+              do sleep 2; done
+              echo "Init: creating placeholder site..."
+              WORK=$(mktemp -d)
+              mkdir -p "$WORK/__init__"
+              echo "initialized" > "$WORK/__init__/index.html"
+              tar cf /tmp/init.tar -C "$WORK" __init__
+              curl -sf -X PUT "http://git-pages:3000/" \
+                -H "Host: {{ .Values.ingress.host }}" \
+                -H "Content-Type: application/x-tar" \
+                --data-binary @/tmp/init.tar -o /dev/null
+              echo "Init: done"
+          env:
+            - name: PAGES_INSECURE
+              value: "1"
+{{- end }}