build(docker): use Node.js 22 for embedded frontend builds (#7076)

# Description of Changes

Updated the NodeSource setup from Node.js 20 to Node.js 22 in all
embedded frontend Docker build variants:

- Standard image
- Fat image
- Ultra-lite image

This aligns the Docker builds with the Node.js version used by the
frontend CI workflows and satisfies the `node >=22` engine requirement
of `rollup-plugin-visualizer@7.0.1`
https://github.com/btd/rollup-plugin-visualizer/commit/2caae97a061c752b9ec0fc5b820d10f0777b4c01
. It removes the `EBADENGINE` warning emitted during `frontend:install`
in the Docker Compose test workflow.

---

## Checklist

### General

- [ ] I have read the [Contribution
Guidelines](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/CONTRIBUTING.md)
- [ ] I have read the [Stirling-PDF Developer
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md)
(if applicable)
- [ ] I have read the [How to add new languages to
Stirling-PDF](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md)
(if applicable)
- [ ] I have performed a self-review of my own code
- [ ] My changes generate no new warnings

### Documentation

- [ ] I have updated relevant docs on [Stirling-PDF's doc
repo](https://github.com/Stirling-Tools/Stirling-Tools.github.io/blob/main/docs/)
(if functionality has heavily changed)
- [ ] I have read the section [Add New Translation
Tags](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/HowToAddNewLanguage.md#add-new-translation-tags)
(for new translation tags only)

### Translations (if applicable)

- [ ] I ran
[`scripts/counter_translation.py`](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/docs/counter_translation.md)

### UI Changes (if applicable)

- [ ] Screenshots or videos demonstrating the UI changes are attached
(e.g., as comments or direct attachments in the PR)

### Testing (if applicable)

- [ ] I have run `task check` to verify linters, typechecks, and tests
pass
- [ ] I have tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/DeveloperGuide.md#7-testing)
for more details.

docker/embedded/Dockerfile

@@ -11,7 +11,7 @@ ARG TASK_VERSION=3.49.1
 RUN apt-get update \
     && apt-get install -y --no-install-recommends curl ca-certificates \
     && update-ca-certificates \
-    && curl -fsSL https://deb.nodesource.com/setup_20.x | bash - \
+    && curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \
     && ARCH=$(dpkg --print-architecture) \
     && curl -fsSL "https://github.com/go-task/task/releases/download/v${TASK_VERSION}/task_${TASK_VERSION}_linux_${ARCH}.deb" -o /tmp/task.deb \

docker/embedded/Dockerfile.fat

@@ -12,7 +12,7 @@ ARG TASK_VERSION=3.49.1
 RUN apt-get update \
     && apt-get install -y --no-install-recommends curl ca-certificates \
     && update-ca-certificates \
-    && curl -fsSL https://deb.nodesource.com/setup_20.x | bash - \
+    && curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \
     && ARCH=$(dpkg --print-architecture) \
     && curl -fsSL "https://github.com/go-task/task/releases/download/v${TASK_VERSION}/task_${TASK_VERSION}_linux_${ARCH}.deb" -o /tmp/task.deb \

docker/embedded/Dockerfile.ultra-lite

@@ -8,7 +8,7 @@ FROM gradle:9.6.0-jdk25@sha256:e3905233ae349e72016daf8a0e19f085a1dd89ded8ec88b3d
 ARG TASK_VERSION=3.49.1
 RUN apt-get update && apt-get install -y --no-install-recommends \
     curl \
-    && curl -fsSL https://deb.nodesource.com/setup_20.x | bash - \
+    && curl -fsSL https://deb.nodesource.com/setup_22.x | bash - \
     && apt-get install -y --no-install-recommends nodejs \
     && npm --version \
     && node --version \