build: script to publish web/worker images to the Gitea registry

Adds scripts/build-push.sh (build + push lyra-web/lyra-worker :latest and
:<sha> to git.jger.nl) + a README 'Deploying to a server (pre-built images)'
section. The server pulls these via the vm-download ops repo (docker/lyra).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

scripts/build-push.sh

@@ -0,0 +1,29 @@
+#!/usr/bin/env bash
+# Build the Lyra web + worker images and push them to the Gitea container registry, so the VM
+# can pull pre-built images instead of building from source.
+#
+# Usage (from the Lyra repo root):
+#   docker login git.jger.nl        # once — Gitea username + a token with package:write
+#   ./scripts/build-push.sh         # builds + pushes :latest and :<short-sha>
+#
+# Override the registry namespace with LYRA_REGISTRY (default git.jger.nl/jonathan).
+set -euo pipefail
+
+REGISTRY="${LYRA_REGISTRY:-git.jger.nl/jonathan}"
+here="$(cd "$(dirname "$0")/.." && pwd)"
+sha="$(git -C "$here" rev-parse --short HEAD)"
+
+for svc in web worker; do
+  img="$REGISTRY/lyra-$svc"
+  echo "==> building $img ($sha)"
+  docker build -t "$img:latest" -t "$img:$sha" "$here/$svc"
+done
+
+for svc in web worker; do
+  img="$REGISTRY/lyra-$svc"
+  echo "==> pushing $img:latest and $img:$sha"
+  docker push "$img:latest"
+  docker push "$img:$sha"
+done
+
+echo "Done. Pulled on the VM with: docker compose pull && docker compose up -d"