Add audit system, invite links, and usage analytics (#4749)

# Description of Changes

New Features
Audit System: Complete audit logging with dashboard, event tracking, and
export capabilities

Invite Links: Secure invite system with email notifications and
expiration

Usage Analytics: Endpoint usage statistics and visualization

License Management: User counting with grandfathering and license
enforcement
## 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)

### 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.

---------

Co-authored-by: James Brunton <[email protected]>

frontend/src/core/utils/settingsPendingHelper.ts

@@ -50,12 +50,19 @@ export function isFieldPending<T extends SettingsWithPending>(
   fieldPath: string
 ): boolean {
   if (!settings?._pending) {
+    console.log(`[isFieldPending] No _pending block found for field: ${fieldPath}`);
     return false;
   }
 
   // Navigate the pending object using dot notation
   const value = getNestedValue(settings._pending, fieldPath);
-  return value !== undefined;
+  const isPending = value !== undefined;
+
+  if (isPending) {
+    console.log(`[isFieldPending] Field ${fieldPath} IS pending with value:`, value);
+  }
+
+  return isPending;
 }
 
 /**