Bump node from 20-alpine to 25-alpine

Bumps node from 20-alpine to 25-alpine.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 25-alpine
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

Dockerfile

@@ -1,5 +1,5 @@
 # ── Stage 1: Build frontend ────────────────────────────────────────────────────
-FROM node:20-alpine AS frontend-builder
+FROM node:25-alpine AS frontend-builder
 WORKDIR /app/frontend
 COPY frontend/package*.json ./
 RUN npm ci --prefer-offline