feat(FN-1343): add rust, copper, foundry, carbon color themes

- Add rust, copper, foundry, carbon theme IDs to core types
- Register themes in ThemeSelector component and flash-prevention logic
- Add CSS theme blocks and swatches for all four new themes
- Add ThemeSelector unit tests for the new themes
- Update memory documentation with new theme count

packages/desktop/src/renderer/index.html

@@ -41,6 +41,10 @@
             "palenight",
             "monokai-pro",
             "slime",
+            "rust",
+            "copper",
+            "foundry",
+            "carbon",
           ];
 
           if (!validThemes.includes(colorTheme)) {