Add --load-images to the kind demo

Pulls the demo's images on the host and loads them into the kind node,
since the node may not trust the TLS chain to git.ryuvia.com. Tags come
from the chart's appVersion, 01-server.yaml and 00-postgres.yaml, so a
bumped pin is picked up. A full run does the same first unless
PRELOAD_IMAGES=false; PULL_ALWAYS=true re-pulls tags the host has.

Images are saved for the host platform and loaded as an archive: `kind
load docker-image` imports with --all-platforms, which fails for a
multi-arch image under docker's containerd image store.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

examples/demo/README.md

@@ -18,6 +18,13 @@ few alerts. `./run-demo.sh --help` for the knobs, `./run-demo.sh
 --teardown` to tear it back down. The rest of this file is the manual
 walkthrough it automates.
 
+It pulls the demo's images on the host and loads them into the kind node
+first, since the node may not trust the TLS chain to `git.ryuvia.com`. To
+redo just that step (after bumping a pin, or for a pod stuck in
+`ImagePullBackOff`), run `./run-demo.sh --load-images`; add
+`PULL_ALWAYS=true` to re-pull tags the host already has.
+`PRELOAD_IMAGES=false` skips it in a full run.
+
 ## Prerequisites
 
 - The operator and its CRDs installed and running (`make install