Add Settings -> Database viewer (Adminer) for local devs and any admin

Local dev gets an unauthenticated Adminer instance bound to loopback
only. In production, any account with is_admin=true can open it -
the app mints a short-lived token from a live admin session, which
Nginx's new db.ciagent.org block exchanges for a session cookie that
re-checks admin status on every request, instead of a shared static
password that wouldn't scale to multiple admins or revoke live.

Co-Authored-By: Claude Sonnet 5 <[email protected]>

infrastructure/docker/web.Dockerfile.prod

@@ -17,8 +17,10 @@ COPY apps/web ./
 # *browser* will use, not a Docker-internal service name. See .env.example.
 ARG NEXT_PUBLIC_API_URL
 ARG NEXT_PUBLIC_GIT_REPO_URL
+ARG NEXT_PUBLIC_DB_VIEWER_URL
 ENV NEXT_PUBLIC_API_URL=${NEXT_PUBLIC_API_URL} \
-    NEXT_PUBLIC_GIT_REPO_URL=${NEXT_PUBLIC_GIT_REPO_URL}
+    NEXT_PUBLIC_GIT_REPO_URL=${NEXT_PUBLIC_GIT_REPO_URL} \
+    NEXT_PUBLIC_DB_VIEWER_URL=${NEXT_PUBLIC_DB_VIEWER_URL}
 RUN npm run build