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]>

app/proprietary/src/test/java/stirling/software/proprietary/security/configuration/ee/LicenseKeyCheckerTest.java

@@ -17,11 +17,13 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 
 import stirling.software.common.model.ApplicationProperties;
+import stirling.software.proprietary.service.UserLicenseSettingsService;
 
 @ExtendWith(MockitoExtension.class)
 class LicenseKeyCheckerTest {
 
     @Mock private KeygenLicenseVerifier verifier;
+    @Mock private UserLicenseSettingsService userLicenseSettingsService;
 
     @Test
     void premiumDisabled_skipsVerification() {
@@ -29,7 +31,9 @@ class LicenseKeyCheckerTest {
         props.getPremium().setEnabled(false);
         props.getPremium().setKey("dummy");
 
-        LicenseKeyChecker checker = new LicenseKeyChecker(verifier, props);
+        LicenseKeyChecker checker =
+                new LicenseKeyChecker(verifier, props, userLicenseSettingsService);
+        checker.init();
 
         assertEquals(License.NORMAL, checker.getPremiumLicenseEnabledResult());
         verifyNoInteractions(verifier);
@@ -42,7 +46,9 @@ class LicenseKeyCheckerTest {
         props.getPremium().setKey("abc");
         when(verifier.verifyLicense("abc")).thenReturn(License.PRO);
 
-        LicenseKeyChecker checker = new LicenseKeyChecker(verifier, props);
+        LicenseKeyChecker checker =
+                new LicenseKeyChecker(verifier, props, userLicenseSettingsService);
+        checker.init();
 
         assertEquals(License.PRO, checker.getPremiumLicenseEnabledResult());
         verify(verifier).verifyLicense("abc");
@@ -58,7 +64,9 @@ class LicenseKeyCheckerTest {
         props.getPremium().setKey("file:" + file.toString());
         when(verifier.verifyLicense("filekey")).thenReturn(License.ENTERPRISE);
 
-        LicenseKeyChecker checker = new LicenseKeyChecker(verifier, props);
+        LicenseKeyChecker checker =
+                new LicenseKeyChecker(verifier, props, userLicenseSettingsService);
+        checker.init();
 
         assertEquals(License.ENTERPRISE, checker.getPremiumLicenseEnabledResult());
         verify(verifier).verifyLicense("filekey");
@@ -71,7 +79,9 @@ class LicenseKeyCheckerTest {
         props.getPremium().setEnabled(true);
         props.getPremium().setKey("file:" + file.toString());
 
-        LicenseKeyChecker checker = new LicenseKeyChecker(verifier, props);
+        LicenseKeyChecker checker =
+                new LicenseKeyChecker(verifier, props, userLicenseSettingsService);
+        checker.init();
 
         assertEquals(License.NORMAL, checker.getPremiumLicenseEnabledResult());
         verifyNoInteractions(verifier);