Add photo galleries API and frontend for public and admin viewing.

Introduces the Go photo-api service, nginx/systemd deploy wiring, and Next.js gallery/lightbox pages so event photos can be managed and browsed.

Co-authored-by: Cursor <cursoragent@cursor.com>

photo-api/Dockerfile

@@ -0,0 +1,25 @@
+# Secondary deployment path (the primary is bare-metal systemd, see
+# deploy/spanglish-photos.service). Built for the docker-compose "scale"
+# setup or any container host.
+#
+#   docker build -t spanglish-photo-api photo-api/
+#   docker run --env-file photo-api/.env -p 3020:3020 spanglish-photo-api
+
+FROM golang:1.26 AS build
+WORKDIR /src
+COPY go.mod go.sum ./
+RUN go mod download
+COPY . .
+RUN CGO_ENABLED=0 go build -trimpath -ldflags="-s -w" -o /photo-api ./cmd/photo-api
+
+# debian-slim rather than distroless: HEIC conversion needs the libvips CLI.
+FROM debian:bookworm-slim
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends libvips-tools ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+COPY --from=build /photo-api /usr/local/bin/photo-api
+RUN useradd -r -u 10001 photoapi && mkdir -p /data/photos && chown photoapi /data/photos
+USER photoapi
+ENV STORAGE_PATH=/data/photos
+EXPOSE 3020
+ENTRYPOINT ["/usr/local/bin/photo-api"]