fix(chat,docker): return 503 for rate-limited providers and bundle node-machine-id

- chat: always return 503 Service Unavailable when all credentials are rate-limited
- Dockerfile: explicitly copy node-machine-id into standalone runtime image

Dockerfile

@@ -40,6 +40,8 @@ COPY --from=builder /app/node_modules/next ./node_modules/next
 # sql.js loads dist/sql-wasm.wasm by path at runtime; tracing only follows JS imports,
 # so the last-resort DB driver would abort with ENOENT on the missing binary.
 COPY --from=builder /app/node_modules/sql.js ./node_modules/sql.js
+# node-machine-id is createRequire-loaded at runtime; tracing omits it.
+COPY --from=builder /app/node_modules/node-machine-id ./node_modules/node-machine-id
 
 RUN mkdir -p /app/data && chown -R node:node /app && \
   mkdir -p /app/data-home && chown node:node /app/data-home && \