Security fixes, enterprise stuff and more (#3241)

# Description of Changes

Please provide a summary of the changes, including:

- Enable user to add custom JAVA ops with env JAVA_CUSTOM_OPTS
- Added support for prometheus (enabled via JAVA_CUSTOM_OPTS +
enterprise license)
- Changed settings from enterprise naming to 'Premium'
- KeygenLicense Check to support offline licenses
- Disable URL-to-PDF due to huge security bug
- Remove loud Split PDF logs
- addUsers renamed to adminSettings
- Added Usage analytics page
- Add user button to only be enabled based on total users free
- Improve Merge memory usage


Closes #(issue_number)

---

## 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/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/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/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/DeveloperGuide.md#6-testing)
for more details.

---------

Co-authored-by: a <a>
Co-authored-by: pixeebot[bot] <104101892+pixeebot[bot]@users.noreply.github.com>
Co-authored-by: Connor Yoh <con.yoh13@gmail.com>

src/main/java/stirling/software/SPDF/model/ApplicationProperties.java

@@ -81,6 +81,8 @@ public class ApplicationProperties {
     private Endpoints endpoints = new Endpoints();
     private Metrics metrics = new Metrics();
     private AutomaticallyGenerated automaticallyGenerated = new AutomaticallyGenerated();
+
+    private Premium premium = new Premium();
     private EnterpriseEdition enterpriseEdition = new EnterpriseEdition();
     private AutoPipeline autoPipeline = new AutoPipeline();
     private ProcessExecutor processExecutor = new ProcessExecutor();
@@ -287,6 +289,7 @@ public class ApplicationProperties {
         private Boolean enableAnalytics;
         private Datasource datasource;
         private Boolean disableSanitize;
+        private Boolean enableUrlToPDF;
         private CustomPaths customPaths = new CustomPaths();
 
         public boolean isAnalyticsEnabled() {
@@ -390,6 +393,7 @@ public class ApplicationProperties {
         private String appVersion;
     }
 
+    // TODO: Remove post migration
     @Data
     public static class EnterpriseEdition {
         private boolean enabled;
@@ -415,6 +419,50 @@ public class ApplicationProperties {
         }
     }
 
+    @Data
+    public static class Premium {
+        private boolean enabled;
+        @ToString.Exclude private String key;
+        private int maxUsers;
+        private ProFeatures proFeatures = new ProFeatures();
+        private EnterpriseFeatures enterpriseFeatures = new EnterpriseFeatures();
+
+        @Data
+        public static class ProFeatures {
+            private boolean ssoAutoLogin;
+            private CustomMetadata customMetadata = new CustomMetadata();
+
+            @Data
+            public static class CustomMetadata {
+                private boolean autoUpdateMetadata;
+                private String author;
+                private String creator;
+                private String producer;
+
+                public String getCreator() {
+                    return creator == null || creator.trim().isEmpty() ? "Stirling-PDF" : creator;
+                }
+
+                public String getProducer() {
+                    return producer == null || producer.trim().isEmpty()
+                            ? "Stirling-PDF"
+                            : producer;
+                }
+            }
+        }
+
+        @Data
+        public static class EnterpriseFeatures {
+            private PersistentMetrics persistentMetrics = new PersistentMetrics();
+
+            @Data
+            public static class PersistentMetrics {
+                private boolean enabled;
+                private int retentionDays;
+            }
+        }
+    }
+
     @Data
     public static class ProcessExecutor {
         private SessionLimit sessionLimit = new SessionLimit();