init: git-pages init job, ADR 0004, docs, remove PUT fallback

- ADR 0004: commit-status-periaate (API vain tarvittaessa, natiivi riittää)
- git-pages/docs/implementation-notes.md: tekniset huomiot
- init-job.yaml: post-install hook luo placeholderin (.index olemassa)
- values.yaml: initJob.enabled default
- publish-git-pages.sh: poistettu PUT-fallback (init job hoitaa)
- README: maininta automaattisesta initistä

scripts/publish-git-pages.sh

@@ -50,15 +50,6 @@ publish() {
 
 HTTP_CODE=$(publish PATCH)
 
-if [ "$HTTP_CODE" = "503" ]; then
-  HTTP_CODE=$(curl -sS -X PUT "$PUBLISH_SITE_URL" \
-    -u "${GIT_PAGES_PUBLISH_USER}:${GIT_PAGES_PUBLISH_TOKEN}" \
-    -H "Content-Type: application/x-tar" \
-    --data-binary @"$TAR" \
-    -o /tmp/git-pages-publish-response.txt \
-    -w "%{http_code}")
-fi
-
 case "$HTTP_CODE" in
   200|201|204) ;;
   *)