feat: caption-ninja recipe (web pages, private relay, Caption Local STT)

Self-hosted live captioning from steveseguin/captionninja and
steveseguin/caption-local. Upstream publishes no images, so images/build.sh
builds them from pinned commits.

images/build.sh

@@ -0,0 +1,46 @@
+#!/usr/bin/env bash
+# Build the three caption-ninja images from pinned upstream commits.
+#
+# Upstream publishes no images, so we build them ourselves. Run this on a
+# Docker host (it needs no registry credentials); the images are tagged with
+# their final registry names so a single-node swarm can deploy them directly.
+# See README.md "Images" for pushing them to the registry afterwards.
+#
+#   usage: images/build.sh [workdir]
+set -euo pipefail
+
+REGISTRY=git.autonomic.zone/recipe-maintainers
+CAPTIONNINJA_COMMIT=dfcee8f551a2b175740ab9f73e3787e1458cce2d
+CAPTION_LOCAL_COMMIT=7d759fe1eae100ccdb5de0eea82438c941b26582
+RELAY_VERSION=0.2.0       # captionninja relay/package.json
+CAPTION_LOCAL_VERSION=1.1.0  # caption-local VERSION
+WEB_VERSION=2026.09.07    # captionninja has no releases: date of CAPTIONNINJA_COMMIT
+
+here="$(cd -- "$(dirname -- "${BASH_SOURCE[0]}")" && pwd)"
+work="${1:-$(mktemp -d)}"
+
+checkout() {  # url commit dir
+    rm -rf "$3"
+    git init -q "$3"
+    git -C "$3" fetch -q --depth 1 "$1" "$2"
+    git -C "$3" checkout -q FETCH_HEAD
+}
+
+checkout https://github.com/steveseguin/captionninja "$CAPTIONNINJA_COMMIT" "$work/captionninja"
+checkout https://github.com/steveseguin/caption-local "$CAPTION_LOCAL_COMMIT" "$work/caption-local"
+
+cn="${CAPTIONNINJA_COMMIT:0:7}"
+cl="${CAPTION_LOCAL_COMMIT:0:7}"
+
+docker build -t "$REGISTRY/caption-ninja-web:$WEB_VERSION-$cn" \
+    -f "$here/web/Dockerfile" "$work/captionninja"
+docker build -t "$REGISTRY/caption-ninja-relay:$RELAY_VERSION-$cn" \
+    "$work/captionninja/relay"
+docker build -t "$REGISTRY/caption-ninja-stt:$CAPTION_LOCAL_VERSION-$cl" \
+    "$work/caption-local"
+
+echo
+echo "Built:"
+echo "  $REGISTRY/caption-ninja-web:$WEB_VERSION-$cn"
+echo "  $REGISTRY/caption-ninja-relay:$RELAY_VERSION-$cn"
+echo "  $REGISTRY/caption-ninja-stt:$CAPTION_LOCAL_VERSION-$cl"