Bump node from 22.16.0-alpine to 25.1.0-alpine in /backend

Bumps node from 22.16.0-alpine to 25.1.0-alpine.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 25.1.0-alpine
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

backend/Dockerfile

@@ -1,5 +1,5 @@
 # base
-FROM node:22.16.0-alpine AS base
+FROM node:25.1.0-alpine AS base
 
 WORKDIR /app