Use Flood v4.16.2 with Node 24 and retain startup validation

Dockerfile.client

@@ -2,7 +2,7 @@
 # Build from a clean upstream release checkout using the Gitea workflow.
 
 ARG BUILDPLATFORM=amd64
-ARG NODE_IMAGE=docker.io/node:22-alpine3.24
+ARG NODE_IMAGE=docker.io/node:24-alpine3.24
 
 FROM --platform=$BUILDPLATFORM ${NODE_IMAGE} as nodebuild
 
@@ -11,12 +11,12 @@ WORKDIR /usr/src/app/
 # Copy project files
 COPY . ./
 
-# Flood v4.7.0 uses package-lock.json, not pnpm.
-RUN npm ci --legacy-peer-deps --omit=optional
+# Use the package manager and lockfile declared by the upstream release.
+RUN npm install -g corepack && corepack enable && corepack install
+RUN pnpm install --frozen-lockfile
 
-# The v4.7 Webpack toolchain needs legacy hashing with modern Node/OpenSSL.
-# This option applies only to asset compilation, not the running server.
-RUN NODE_OPTIONS=--openssl-legacy-provider npm run build-assets
+# Build Flood server and client assets.
+RUN npm run build
 
 # Now get the clean Node.js image
 FROM ${NODE_IMAGE} as flood