Bsky link card service (#4547)

* setup bskycard

* quick proof of concept for png card generation

* bskycard: use jsx

* bskycard: 3x5 profile layout

* bskycard: add butterfly overlay

* bskycard: tidy

* bskycard: separate and reorganize

* bskycard: tidy

* bskycard: tidy

* bskycard: tidy

* bskycard: poc of transparent overlay and box shadow

* bskycard: reorg impl into src/ directory

* bskycard: use more standard app structure

* bskycard: setup dockerfile, fix build

* bskycard: support for x-origin-verify

* bskycard: card layout, filter images based on labels

* bskycard: tidy

* bskycard: support cluster mode

* bskycard: handle error fetching starter pack info

* bskycard: tidy

* bskycard: fix leak on failed image fetch

* bskycard: build workflow

* bskyogcard: rename from bskycard

* bskyogcard: fix some express plumbing

* bskyogcard: add cdn tags, tidy

Dockerfile.bskyogcard

@@ -0,0 +1,41 @@
+FROM node:20.11-alpine3.18 as build
+
+# Move files into the image and install
+WORKDIR /app
+
+COPY ./bskyogcard/package.json ./
+COPY ./bskyogcard/yarn.lock ./
+RUN yarn install --frozen-lockfile
+
+COPY ./bskyogcard ./
+
+# build then prune dev deps
+RUN yarn build
+RUN yarn install --production --ignore-scripts --prefer-offline
+
+# Uses assets from build stage to reduce build size
+FROM node:20.11-alpine3.18
+
+RUN apk add --update dumb-init
+
+# Avoid zombie processes, handle signal forwarding
+ENTRYPOINT ["dumb-init", "--"]
+
+WORKDIR /app
+COPY --from=build /app /app
+RUN mkdir /app/data && chown node /app/data
+
+VOLUME /app/data
+EXPOSE 3000
+ENV CARD_PORT=3000
+ENV NODE_ENV=production
+# potential perf issues w/ io_uring on this version of node
+ENV UV_USE_IO_URING=0
+
+# https://github.com/nodejs/docker-node/blob/master/docs/BestPractices.md#non-root-user
+USER node
+CMD ["node", "--heapsnapshot-signal=SIGUSR2", "--enable-source-maps", "dist/bin.js"]
+
+LABEL org.opencontainers.image.source=https://github.com/bluesky-social/social-app
+LABEL org.opencontainers.image.description="Bsky Card Service"
+LABEL org.opencontainers.image.licenses=UNLICENSED