misc: zot registry, k8s OIDC, server configs, sandbox experiments, and notes

- docker-30/zot: add Zot OCI registry with on-demand sync to docker.io,
  registry.k8s.io, ghcr.io, quay.io
- kubernetes-kvm-terraform: wire Kanidm OIDC via structured
  AuthenticationConfiguration; add reference apiserver manifest and
  join-node-02 helper
- servers: reorganize shadow/ under servers/, add saint vhost config and
  utility-101 VM definition, add shadow hrajfrisbee.cz vhost and
  storage-23 notes
- experiments: add notes and configs for e2b dev VM, kata + firecracker
  on kube, microsandbox, orb-stack k3s (terraform + cloud-init), rke2
- vms/docker: document tailscale + node-exporter setup
- blog: stub post on Gateway API
- chore: gitignore tmp/, smtp_password, and the two local-only
  credential caches; add per-project .claude/settings.json

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

kubernetes-kvm-terraform/files/auth-config.yaml

@@ -0,0 +1,14 @@
+apiVersion: apiserver.config.k8s.io/v1beta1
+kind: AuthenticationConfiguration
+jwt:
+  - issuer:
+      url: https://idm.home.hrajfrisbee.cz/oauth2/openid/k8s
+      audiences:
+        - k8s
+    claimMappings:
+      username:
+        claim: preferred_username
+        prefix: ""
+      groups:
+        claim: groups
+        prefix: ""