fix(docker): carry the migration runner + SQL lineage in the runtime image (#149)

The Railway pre-deploy command `node scripts/migrate-postgres.mjs` was
failing with MODULE_NOT_FOUND — the runtime stage only copied .output and
.contentrain, so scripts/, the postgres/supabase migration SQL, and pg
were absent from /app. Copy the standalone runner + verify script + both
migration dirs, and install a self-contained pg@8.22.0 (its only
non-builtin import) so the pre-deploy command applies migrations before
each release serves.

Co-authored-by: Contentrain <mcp@contentrain.io>

Author: ABB65

Dockerfile

@@ -39,6 +39,19 @@ COPY --from=build /app/.output ./.output
 # Contentrain content (needed for UI strings via @contentrain/query)
 COPY --from=build /app/.contentrain ./.contentrain
 
+# Database migration runner + SQL lineage. The managed pair does NOT migrate
+# at app start; the Railway pre-deploy command (`node scripts/migrate-postgres.mjs`)
+# runs this before the new image serves, so the schema is always applied ahead
+# of the release. The app bundles its own pg inside .output; this standalone
+# runner lives outside that tree, so it gets a self-contained pg (its only
+# non-builtin import, matched to the app's resolved 8.22.0).
+COPY --from=build /app/scripts/migrate-postgres.mjs /app/scripts/verify-managed-schema.mjs ./scripts/
+COPY --from=build /app/postgres/migrations ./postgres/migrations
+COPY --from=build /app/supabase/migrations ./supabase/migrations
+RUN printf '{"name":"studio-migrations","private":true,"type":"module"}\n' > package.json \
+  && npm install --no-fund --no-audit pg@8.22.0 \
+  && npm cache clean --force
+
 # Git needs a writable home for config
 ENV HOME=/home/studio
 ENV NODE_ENV=production