Builds custom Jar (#5029)

# Description of Changes

Change jar files to contain frontend if provided with param, else
doesnt... add release artifact -server version which wont have frontend

---

## 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/devGuide/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 tested my changes locally. Refer to the [Testing
Guide](https://github.com/Stirling-Tools/Stirling-PDF/blob/main/devGuide/DeveloperGuide.md#6-testing)
for more details.

docker/Dockerfile.unified-lite

@@ -10,7 +10,9 @@ COPY frontend/package.json frontend/package-lock.json ./
 RUN npm ci
 
 COPY frontend .
-RUN DISABLE_ADDITIONAL_FEATURES=true npm run build
+# Override VITE_API_BASE_URL to use relative paths for production
+# This ensures frontend works with nginx proxy setup
+RUN DISABLE_ADDITIONAL_FEATURES=true VITE_API_BASE_URL=/ npm run build
 
 # Stage 2: Build Backend
 FROM gradle:8.14-jdk21 AS backend-build
@@ -76,7 +78,6 @@ ENV DISABLE_ADDITIONAL_FEATURES=false \
     TMP=/tmp/stirling-pdf \
     MODE=BOTH \
     BACKEND_INTERNAL_PORT=8081 \
-    VITE_API_BASE_URL=http://localhost:8080 \
     ENDPOINTS_GROUPS_TO_REMOVE=CLI
 
 # Install minimal dependencies