feat(deploy): portainer stack template for federation test instances [FED-M2-DEPLOY-02]

Add deploy/portainer/federated-test.stack.yml — a Docker Swarm-compatible
Compose file for Portainer that boots a federated-tier gateway (gateway +
pgvector/pg17 + valkey:8-alpine) with Traefik HTTPS labels and digest-pinned
image (fed-v0.1.0-m1). Parameterised via STACK_NAME/HOST_FQDN for reuse
across mos-test-1 and mos-test-2 in DEPLOY-03/04. Add deploy/portainer/README.md
with deployment instructions, required env vars, and external resource notes.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

docker/gateway.Dockerfile

@@ -5,27 +5,18 @@ RUN corepack enable
 
 FROM base AS builder
 WORKDIR /app
-# Copy workspace manifests first for layer-cached install
 COPY pnpm-workspace.yaml pnpm-lock.yaml package.json ./
 COPY apps/gateway/package.json ./apps/gateway/
 COPY packages/ ./packages/
-COPY plugins/ ./plugins/
 RUN pnpm install --frozen-lockfile
 COPY . .
-# Build gateway and all of its workspace dependencies via turbo dependency graph
+RUN pnpm --filter @mosaic/gateway build
-RUN pnpm turbo run build --filter @mosaicstack/gateway...
-# Produce a self-contained deploy artifact: flat node_modules, no pnpm symlinks
-# --legacy is required for pnpm v10 when inject-workspace-packages is not set
-RUN pnpm --filter @mosaicstack/gateway --prod deploy --legacy /deploy
 
 FROM base AS runner
 WORKDIR /app
 ENV NODE_ENV=production
-# Use the pnpm deploy output — resolves all deps into a flat, self-contained node_modules
-COPY --from=builder /deploy/node_modules ./node_modules
-COPY --from=builder /deploy/package.json ./package.json
-# dist is declared in package.json "files" so pnpm deploy copies it into /deploy;
-# copy from builder explicitly as belt-and-suspenders
 COPY --from=builder /app/apps/gateway/dist ./dist
+COPY --from=builder /app/apps/gateway/package.json ./package.json
+COPY --from=builder /app/node_modules ./node_modules
 EXPOSE 4000
 CMD ["node", "dist/main.js"]