build(deps): bump library/node from 20-alpine to 26-alpine

Bumps library/node from 20-alpine to 26-alpine.

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

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

Dockerfile.nonroot

@@ -5,7 +5,7 @@
 ARG BASE_URL=
 
 # Build stage (identical to main Dockerfile)
-FROM mirror.gcr.io/library/node:20-alpine AS builder
+FROM mirror.gcr.io/library/node:26-alpine AS builder
 WORKDIR /app
 COPY package*.json ./
 COPY vendor ./vendor