Customise window decorations, add openfolder action to menu, fix toolbar colours

src/theme.scss

@@ -0,0 +1,10 @@
+@use "@angular/material" as mat;
+
+$rose-theme: mat.define-theme(
+  (
+    color: (
+      theme-type: dark,
+      primary: mat.$rose-palette,
+    ),
+  )
+);