chore(deps): bump node in /containers/app

Bumps node from 24.8-trixie-slim to 25.8-trixie-slim.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 25.8-trixie-slim
  dependency-type: direct:production
...

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

Author: dependabot[bot]

containers/app/Dockerfile

@@ -1,5 +1,5 @@
 ARG OPENHANDS_BUILD_VERSION=dev
-FROM node:24.8-trixie-slim AS frontend-builder
+FROM node:25.8-trixie-slim AS frontend-builder
 
 WORKDIR /app