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>

experiments/orb-stack/modules/base-template/cloud-init-base.yaml

@@ -0,0 +1,27 @@
+#cloud-config
+hostname: ${hostname}
+manage_etc_hosts: true
+
+# Kernel modules for container networking
+write_files:
+  - path: /etc/modules-load.d/k8s.conf
+    content: |
+      overlay
+      br_netfilter
+  - path: /etc/sysctl.d/k8s.conf
+    content: |
+      net.bridge.bridge-nf-call-iptables  = 1
+      net.bridge.bridge-nf-call-ip6tables = 1
+      net.ipv4.ip_forward                 = 1
+
+packages:
+  - curl
+  - gpg
+  - apt-transport-https
+
+runcmd:
+  - modprobe overlay
+  - modprobe br_netfilter
+  - sysctl --system
+  - swapoff -a
+  - sed -i '/ swap / s/^\(.*\)$/#\1/g' /etc/fstab