feat: deploy through shared Caddy ingress

docker/backend.Dockerfile

@@ -0,0 +1,28 @@
+FROM golang:1.24-alpine AS builder
+
+WORKDIR /src
+RUN apk add --no-cache ca-certificates git
+
+COPY go.mod go.sum ./
+RUN go mod download
+
+COPY . .
+RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/api ./cmd/api \
+    && CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/worker ./cmd/worker \
+    && CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/migrate ./cmd/migrate \
+    && CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/importer ./cmd/importer \
+    && CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/admin ./cmd/admin
+
+FROM alpine:3.22
+
+RUN apk add --no-cache ca-certificates tzdata wget \
+    && addgroup -S -g 10001 app \
+    && adduser -S -D -H -u 10001 -G app app
+
+WORKDIR /app
+COPY --from=builder /out/ /app/
+COPY --from=builder /src/migrations/ /app/migrations/
+
+USER app:app
+EXPOSE 8080
+CMD ["/app/api"]