huskies: merge 1110 story Chat bootstrap Phase 2b: additional stack overlays (Go, Python, Ruby, JVM)

docker/stacks/ruby/Dockerfile.fragment

@@ -0,0 +1,28 @@
+# Ruby stack overlay fragment.
+#
+# Layer this on top of huskies-project-base to produce a project container
+# with Ruby, Bundler, and ruby-lsp (the Shopify Ruby language server).
+#
+# Build the combined image:
+#   (echo "FROM huskies-project-base"; \
+#    cat docker/stacks/ruby/Dockerfile.fragment) | \
+#   docker build -t huskies-project-ruby -
+#
+# Adding a new stack: create docker/stacks/<name>/Dockerfile.fragment and
+# docker/stacks/<name>/markers — no changes to orchestration code required.
+
+USER root
+
+# Ruby runtime, development headers (needed by native gem extensions), and Bundler.
+RUN apt-get update && apt-get install -y --no-install-recommends \
+        ruby \
+        ruby-dev \
+        bundler \
+        build-essential \
+    && rm -rf /var/lib/apt/lists/*
+
+# ruby-lsp: Shopify's Ruby language server (LSP-compliant, actively maintained).
+# Installed globally so the `ruby-lsp` binary is available on PATH.
+RUN gem install ruby-lsp
+
+USER huskies