Refactor: Remove obsolete JavaScript managers and utilities

- Deleted NavigationManager, RecentPlotsManager, SearchManager, SortManager, StatsManager, ThemeManager, Utils, and ViewManager classes.
- Updated gallery builder to improve asset copying logic with a more efficient modification time check.
- Cleaned up gallery HTML template by removing subdirectory listing and embedding gallery data as JSON.
- Added CLAUDE.md for project documentation and guidelines.

gallery/assets/css/main.css

@@ -1,33 +0,0 @@
-/* ========================================
-   GALLERY STYLES - MAIN ENTRY POINT
-   ======================================== */
-
-/* Core styles */
-@import url('./variables.css');
-@import url('./base.css');
-
-/* Component styles */
-@import url('./navigation.css');
-@import url('./search.css');
-@import url('./folder-tree.css');
-@import url('./grid.css');
-@import url('./sidebar.css');
-@import url('./floating-elements.css');
-@import url('./stats.css');
-@import url('./comparison.css');
-@import url('./metadata.css');
-@import url('./metadata-section.css');
-@import url('./folder-metadata.css');
-@import url('./export.css');
-
-/* View controls - must come after grid.css to override */
-@import url('./view-controls.css');
-
-/* Sort controls styling */
-@import url('./sort-controls.css');
-
-/* View override - force grid layout to work */
-@import url('./view-override.css');
-
-/* Responsive design - last to override everything */
-@import url('./responsive.css');