chore(deps): bump node from 20-alpine to 26-alpine

Bumps node from 20-alpine to 26-alpine.

---
updated-dependencies:
- dependency-name: node
  dependency-version: 26-alpine
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Dockerfile

@@ -1,5 +1,5 @@
 # Stage 1: Build UI (arch-independent, runs on build platform)
-FROM --platform=$BUILDPLATFORM node:20-alpine@sha256:fb4cd12c85ee03686f6af5362a0b0d56d50c58a04632e6c0fb8363f609372293 AS ui-builder
+FROM --platform=$BUILDPLATFORM node:26-alpine@sha256:a2dc166a387cc6ca1e62d0c8e265e49ca985d6e60abc9fe6e6c3d6ce8e63f606 AS ui-builder
 WORKDIR /app/ui
 COPY ui/package.json ui/package-lock.json ./
 RUN npm ci