fix: resolve heredoc parsing error in deploy-oci Makefile target

Extract inline Dockerfile to Dockerfile.oci and scp it instead of
generating it via heredoc over SSH. Make's line-continuation backslash
was causing the heredoc delimiter to be parsed as 'DEOFnFROM' by the
remote shell, breaking the image build step.

Dockerfile.oci

@@ -0,0 +1,9 @@
+FROM alpine:3.21
+RUN apk add --no-cache git ca-certificates
+WORKDIR /app
+COPY repo-vis-server ./
+COPY dist ./web/dist/
+ENV PORT=8080
+ENV FRONTEND_DIR=./web/dist
+EXPOSE 8080
+CMD ["./repo-vis-server"]