fix(docs/deploy): harden public docs deployment and pin images

Add a pod-level security context to the nginx container in the public
docs deployment (non-root uid 101, dropped capabilities, read-only
root filesystem, RuntimeDefault seccomp) and rebind it to unprivileged
port 8080 so it does not need CAP_NET_BIND_SERVICE. The nginx PID and
proxy temp paths move under a tmpfs-backed emptyDir so the read-only
root filesystem does not break startup.

Replace the mutable :main tags on both containers with immutable
sha256 digests and switch imagePullPolicy to IfNotPresent so each
rollout references an auditable artifact instead of whatever happens
to be tagged :main when the pod starts. The docs-deploy workflow now
overlays the freshly built docs digest via `kustomize edit set image`
so the manifest stays accurate without a manual edit on each push to
main. The docs Dockerfile pins its node and nginx-micro base images
to specific versions for the same reason.

Ref: AWOO-011, AWOO-012
Assisted-by: Claude Opus 4.7 via Claude Code
Signed-off-by: Xe Iaso <me@xeiaso.net>

.github/actions/spelling/expect.txt

@@ -318,6 +318,7 @@ screenshots
 searchbot
 searx
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+seccomp
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 selfsigned
 Semrush