Improved Configuration and YAML Management (#2966)

# Description of Changes

**What was changed:**
- **Configuration Updates:**  
Replaced all calls to `GeneralUtils.saveKeyToConfig` with the new
`GeneralUtils.saveKeyToSettings` method across multiple classes (e.g.,
`LicenseKeyChecker`, `InitialSetup`, `SettingsController`, etc.). This
update ensures consistent management of configuration settings.
  
- **File Path and Exception Handling:**  
Updated file path handling in `SPDFApplication` by creating `Path`
objects from string paths and logging these paths for clarity. Also
refined exception handling by catching more specific exceptions (e.g.,
using `IOException` instead of a generic `Exception`).

- **Analytics Flag and Rate Limiting:**  
Changed the analytics flag in the application properties from a `String`
to a `Boolean`, and updated related logic in `AppConfig` and
`PostHogService`. The rate-limiting property retrieval in `AppConfig`
was also refined for clarity.

- **YAML Configuration Management:**  
Replaced the previous manual, line-based YAML merging logic in
`ConfigInitializer` with a new `YamlHelper` class. This helper leverages
the SnakeYAML engine to load, update, and save YAML configurations more
robustly while preserving comments and formatting.

**Why the change was made:**
- **Improved Maintainability:**  
Consolidating configuration update logic into a single utility method
(`saveKeyToSettings`) reduces code duplication and simplifies future
maintenance.
  
- **Enhanced Robustness:**  
The new `YamlHelper` class ensures that configuration files are merged
accurately and safely, minimizing risks of data loss or format
corruption.
  
- **Better Type Safety and Exception Handling:**  
Switching the analytics flag to a Boolean and refining exception
handling improves code robustness and debugging efficiency.
  
- **Clarity and Consistency:**  
Standardizing file path handling and logging practices enhances code
readability across the project.

**Challenges encountered:**
- **YAML Merging Complexity:**  
Integrating the new `YamlHelper` required careful handling to preserve
existing settings, comments, and formatting during merges.
  
- **Type Conversion and Backward Compatibility:**  
Updating the analytics flag from a string to a Boolean required
extensive testing to ensure backward compatibility and proper
functionality.
  
- **Exception Granularity:**  
Refactoring exception handling from a generic to a more specific
approach involved a detailed review to cover all edge cases.

Closes #<issue_number>

---

## Checklist

- [x] 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)
- [x] I have performed a self-review of my own code
- [x] 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)

- [x] 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: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>

src/main/resources/settings.yml.template

@@ -86,7 +86,7 @@ system:
   showUpdateOnlyAdmin: false # only admins can see when a new update is available, depending on showUpdate it must be set to 'true'
   customHTMLFiles: false # enable to have files placed in /customFiles/templates override the existing template HTML files
   tessdataDir: /usr/share/tessdata # path to the directory containing the Tessdata files. This setting is relevant for Windows systems. For Windows users, this path should be adjusted to point to the appropriate directory where the Tessdata files are stored.
-  enableAnalytics: 'undefined' # set to 'true' to enable analytics, set to 'false' to disable analytics; for enterprise users, this is set to true
+  enableAnalytics: null # set to 'true' to enable analytics, set to 'false' to disable analytics; for enterprise users, this is set to true
   disableSanitize: false # set to true to disable Sanitize HTML; (can lead to injections in HTML)
   datasource:
     enableCustomDatabase: false # Enterprise users ONLY, set this property to 'true' if you would like to use your own custom database configuration
@@ -111,7 +111,7 @@ ui:
   appName: '' # application's visible name
   homeDescription: '' # short description or tagline shown on the homepage
   appNameNavbar: '' # name displayed on the navigation bar
-  languages: [] # If empty, all languages ​​are enabled. To display only German and Polish ["de_DE", "pl_PL"]. British English is always enabled.
+  languages: [] # If empty, all languages are enabled. To display only German and Polish ["de_DE", "pl_PL"]. British English is always enabled.
 
 endpoints:
   toRemove: [] # list endpoints to disable (e.g. ['img-to-pdf', 'remove-pages'])