chore(deps): bump node from 20-slim to 25-slim in /template

Bumps node from 20-slim to 25-slim.

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

template/Dockerfile.jinja

@@ -1,7 +1,7 @@
 # syntax=docker/dockerfile:1
 {% if frontend == 'htmx-tailwind' and frontend_bundling == 'vite' -%}
 # Build frontend assets
-FROM node:20-slim AS frontend-builder
+FROM node:25-slim AS frontend-builder
 
 WORKDIR /app/frontend