chore: pin Node.js toolchain to 26.10.0

Align the active runtime with the pinned version across .nvmrc, package.json
engines and the Dockerfile base images, so scripts/check-node-toolchain.mjs
passes on the CI host running Node 26.10.0.

Dockerfile

@@ -1,6 +1,6 @@
 # syntax=docker/dockerfile:1
 # Pin the runtime to the supported engine; update both stages deliberately.
-FROM node:26.9.0-alpine AS migrations
+FROM node:26.10.0-alpine AS migrations
 WORKDIR /app
 ENV NEXT_TELEMETRY_DISABLED=1
 # Keep the bootstrap aligned with package.json packageManager.
@@ -42,7 +42,7 @@ RUN --mount=type=cache,target=/app/.next/cache \
     pnpm run build \
     && PERFORMANCE_COMMIT_SHA="$NEXT_DEPLOYMENT_ID" node scripts/performance-report.mjs --output-dir build-reports
 
-FROM node:26.9.0-alpine AS runner
+FROM node:26.10.0-alpine AS runner
 ARG NEXT_DEPLOYMENT_ID="unknown"
 LABEL org.opencontainers.image.revision="$NEXT_DEPLOYMENT_ID"
 WORKDIR /app