Settings display demo and login fix (#4884)

# Description of Changes
<img width="1569" height="980" alt="image"
src="https://github.com/user-attachments/assets/dca1c227-ed84-4393-97a1-e3ce6eb1620b"
/>

<img width="1596" height="935" alt="image"
src="https://github.com/user-attachments/assets/2003e1be-034a-4cbb-869e-6d5d912ab61d"
/>

<img width="1543" height="997" alt="image"
src="https://github.com/user-attachments/assets/fe0c4f4b-eeee-4db4-a041-e554f350255a"
/>


---

## 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.

app/core/src/main/java/stirling/software/SPDF/controller/api/misc/ConfigController.java

@@ -10,6 +10,8 @@ import org.springframework.web.bind.annotation.RequestParam;
 
 import io.swagger.v3.oas.annotations.Hidden;
 
+import lombok.extern.slf4j.Slf4j;
+
 import stirling.software.SPDF.config.EndpointConfiguration;
 import stirling.software.SPDF.config.InitialSetup;
 import stirling.software.common.annotations.api.ConfigApi;
@@ -20,6 +22,7 @@ import stirling.software.common.service.UserServiceInterface;
 
 @ConfigApi
 @Hidden
+@Slf4j
 public class ConfigController {
 
     private final ApplicationProperties applicationProperties;
@@ -59,9 +62,15 @@ public class ConfigController {
             // Extract values from ApplicationProperties
             configData.put("appNameNavbar", applicationProperties.getUi().getAppNameNavbar());
             configData.put("languages", applicationProperties.getUi().getLanguages());
+            configData.put("logoStyle", applicationProperties.getUi().getLogoStyle());
 
             // Security settings
-            configData.put("enableLogin", applicationProperties.getSecurity().getEnableLogin());
+            // enableLogin requires both the config flag AND proprietary features to be loaded
+            // If userService is null, proprietary module isn't loaded
+            // (DISABLE_ADDITIONAL_FEATURES=true or DOCKER_ENABLE_SECURITY=false)
+            boolean enableLogin =
+                    applicationProperties.getSecurity().getEnableLogin() && userService != null;
+            configData.put("enableLogin", enableLogin);
 
             // Mail settings - check both SMTP enabled AND invites enabled
             boolean smtpEnabled = applicationProperties.getMail().isEnabled();

app/core/src/main/resources/settings.yml.template

@@ -176,6 +176,7 @@ system:
 
 ui:
   appNameNavbar: '' # name displayed on the navigation bar
+  logoStyle: classic # Options: 'classic' (default - classic S icon) or 'modern' (minimalist logo)
   languages: [] # If empty, all languages are enabled. To display only German and Polish ["de_DE", "pl_PL"]. British English is always enabled.
 
 endpoints: