Phase 1: warp_engine gem skeleton (path gem, mounted engine)

- libs/ruby/warp_engine: gemspec, WarpEngine::Engine (isolate_namespace with
  empty table_name_prefix), WarpEngine.configure surface (container paths,
  update_secret, image_owners), empty engine routes
- host Gemfile: path gem; host routes: mount WarpEngine::Engine => "/" as
  the last entry so host routes always win
- docker: api build context moved to repo root so libs/ is visible at
  bundle-install time; ./libs:/libs runtime mount; root .dockerignore to keep
  data/ and node_modules out of the build context

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

apps/api/Dockerfile.development

@@ -14,10 +14,13 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
 
 WORKDIR /app
 
-COPY Gemfile ./
+# A path gemek /libs alá kerülnek, ugyanoda, ahova a compose mountolja őket,
+# így a Gemfile "../../libs/..." relatív útvonala build- és futásidőben is stimmel.
+COPY libs /libs
+COPY apps/api/Gemfile ./
 RUN bundle install
 
-COPY . .
+COPY apps/api .
 
 EXPOSE 3000