feat: migrate all container images to Archipelago app registry

All container image references now pull from 80.71.235.15:3000/archipelago/
instead of Docker Hub and ghcr.io. image-versions.sh is the single source
of truth; all scripts use $*_IMAGE variables instead of hardcoded refs.

Files updated:
- scripts/image-versions.sh: central ARCHY_REGISTRY variable
- core/*/config.rs: registry whitelist includes app registry
- core/*/stacks.rs: Immich + Penpot stack images
- scripts/{first-boot,deploy-to-target,container-specs}.sh: use variables
- docker/*/Dockerfile: nginx base image from registry
- image-recipe/: ISO build, podman config, menu script
- scripts/{container-doctor,deploy-bitcoin-knots,fix-indeedhub,validate-app-manifest}.sh

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

image-recipe/scripts/install-podman.sh

@@ -28,10 +28,10 @@ EOF
 mkdir -p /home/archipelago/.config/containers/registries.conf.d
 cat > /home/archipelago/.config/containers/registries.conf.d/000-shortnames.conf <<EOF
 [registries.search]
-registries = ['docker.io', 'quay.io', 'ghcr.io']
+registries = ['80.71.235.15:3000', 'docker.io', 'quay.io', 'ghcr.io']
 
 [registries.insecure]
-registries = []
+registries = ['80.71.235.15:3000']
 
 [registries.block]
 registries = []