frontend: make Docker npm ci resilient to network drops

The frontend dependency install (1000+ packages) failed in Docker with
ECONNRESET / "network aborted" mid-stream. Add npm fetch retries and a long
timeout so a transient registry drop is retried rather than failing the build.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

frontend/Dockerfile

@@ -2,7 +2,13 @@
 FROM node:22-alpine AS deps
 WORKDIR /app
 COPY package*.json ./
-RUN npm ci
+# Retry on transient registry drops (ECONNRESET / "network aborted") and allow a
+# long timeout — the dependency set is large, so a slow connection can stall.
+RUN npm ci --no-audit --no-fund \
+    --fetch-retries=5 \
+    --fetch-retry-mintimeout=20000 \
+    --fetch-retry-maxtimeout=180000 \
+    --fetch-timeout=900000
 
 # --- build (Next.js standalone output) -------------------------------------
 FROM node:22-alpine AS build