Harden frontend Docker npm fetch resilience

doc/operations-and-configuration.md

@@ -42,6 +42,23 @@ Tail logs:
 docker compose logs -f
 ```
 
+## Frontend Build Network Resilience
+
+The frontend image build supports npm fetch tuning through environment-driven compose build args:
+
+- `NPM_REGISTRY` (default `https://registry.npmjs.org/`)
+- `NPM_FETCH_RETRIES` (default `5`)
+- `NPM_FETCH_RETRY_MINTIMEOUT` (default `20000`)
+- `NPM_FETCH_RETRY_MAXTIMEOUT` (default `120000`)
+- `NPM_FETCH_TIMEOUT` (default `300000`)
+- `DOCKER_BUILD_NETWORK` (default `default`; set to `host` on Linux hosts when bridge-network npm fetches time out)
+
+If frontend dependency downloads fail with npm `ETIMEDOUT` during `docker compose build`, keep defaults first, then try:
+
+```bash
+DOCKER_BUILD_NETWORK=host docker compose build --no-cache frontend
+```
+
 ## Authentication Model
 
 - Legacy shared build-time frontend token behavior was removed.