- Add darkMode boolean preference to ApplicationPreference (persisted via java.util.prefs)
- Add ToggleSwitch labeled "Dark Mode" to ApplicationPreferenceEditor
- Add ThemeManager singleton that listens for preference updates and applies/removes
the dark stylesheet to all registered JavaFX Scenes and swaps the Swing LAF
- Add sdrtrunk_dark.css with dark styling for controls, tables, menus, dialogs, charts
- Add FlatLaf dependency for full Swing dark theming (replaces previous OS-specific
MetalLookAndFeel setup; FlatLaf works cross-platform)
- Register all Stages created in JavaFxWindowManager with the ThemeManager and walk
Window.getWindows() at apply-time so unregistered dialogs/alerts also pick up the theme
- Add Foojay toolchain resolver to settings.gradle so Gradle can auto-provision JDK 25
