added a flag to hide settings (#5263)

Added an optional flag in settings.yml to hide the settings button in no
login servers. When hidden, users can no longer:

- Open the Settings modal at all (gear button is hidden)
- Change General preferences (tool picker mode, hide unavailable
tools/conversions, auto‑unzip and file limit)
- Configure keyboard shortcuts (Hotkeys / Keyboard Shortcuts section)
- Use the in‑app update checker UI (see current/latest version, check
for updates, view update details)
- Note: When enableLogin === true, the flag is ignored and the Settings
button remains visible.

---------

Co-authored-by: Anthony Stirling <77850077+Frooodle@users.noreply.github.com>
Co-authored-by: Reece Browne <74901996+reecebrowne@users.noreply.github.com>

app/common/src/main/java/stirling/software/common/model/ApplicationProperties.java

@@ -393,6 +393,7 @@ public class ApplicationProperties {
         private boolean googlevisibility;
         private boolean showUpdate;
         private boolean showUpdateOnlyAdmin;
+        private boolean showSettingsWhenNoLogin = true;
         private boolean customHTMLFiles;
         private String tessdataDir;
         private boolean enableAlphaFunctionality;