Fix React 19 peer conflicts breaking npm ci in Docker build

Dockerfile

@@ -4,9 +4,14 @@ FROM node:22-alpine AS build
 WORKDIR /app
 
 # Safety valve for the 2 GB host: without a cap a runaway build can exhaust the
-# server's RAM and take down neighbouring containers. Measured peak for this app
-# is ~550 MB, so 1 GB leaves headroom while still failing the build rather than
-# the server. Raise this only if the host gets more RAM.
+# server's RAM and take down neighbouring containers, so the build fails instead
+# of the server.
+#
+# Headroom is thinner than it used to be. The old note here recorded a ~550 MB
+# peak; after the React 19 upgrade and adding Astryx the build measures ~967 MB
+# peak RSS, which still completes under this cap but no longer leaves much room.
+# If a future dependency tips it over, raise this only alongside more host RAM —
+# not on its own, which just moves the failure from the build to the machine.
 ENV NODE_OPTIONS=--max-old-space-size=1024
 
 # Install deps from the lockfile first so this layer is reused when only src changes