translations and login page (#5008)

# Description of Changes

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Please provide a summary of the changes, including:

- What was changed
- Why the change was made
- Any challenges encountered

Closes #(issue_number)
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---

## 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/proprietary/src/main/java/stirling/software/proprietary/controller/api/ProprietaryUIDataController.java

@@ -120,6 +120,37 @@ public class ProprietaryUIDataController {
         // Add enableLogin flag so frontend doesn't need to call /app-config
         data.setEnableLogin(securityProps.getEnableLogin());
 
+        // Check if this is first-time setup with default credentials
+        // The isFirstLogin flag captures: default username/password usage and unchanged state
+        boolean isFirstTimeSetup = false;
+        boolean showDefaultCredentials = false;
+
+        List<User> allUsers = userRepository.findAll();
+        List<User> realUsers =
+                allUsers.stream()
+                        .filter(
+                                user ->
+                                        !Role.INTERNAL_API_USER
+                                                .getRoleId()
+                                                .equals(user.getUsername()))
+                        .toList();
+        long userCount = realUsers.size();
+
+        if (userCount == 0) {
+            isFirstTimeSetup = true;
+            showDefaultCredentials = true;
+        } else if (userCount == 1) {
+            Optional<User> adminUser = userRepository.findByUsernameIgnoreCase("admin");
+
+            if (adminUser.isPresent() && Boolean.TRUE.equals(adminUser.get().getIsFirstLogin())) {
+                isFirstTimeSetup = true;
+                showDefaultCredentials = true;
+            }
+        }
+
+        data.setFirstTimeSetup(isFirstTimeSetup);
+        data.setShowDefaultCredentials(showDefaultCredentials);
+
         OAUTH2 oauth = securityProps.getOauth2();
 
         if (oauth != null && oauth.getEnabled()) {
@@ -456,6 +487,8 @@ public class ProprietaryUIDataController {
         private Map<String, String> providerList;
         private String loginMethod;
         private boolean altLogin;
+        private boolean firstTimeSetup;
+        private boolean showDefaultCredentials;
     }
 
     @Data