feat(ground-suite): add system glass themes

ground-suite/README.md

@@ -45,6 +45,13 @@ nix develop -c sh -c 'cd ground-suite && flutter run -d linux'
 Linux is the first tested desktop runner. Native macOS and Windows runners
 will be added only with their respective CI coverage.
 
+## Appearance
+
+Ground Suite supplies light and dark themes and follows the operating system
+by default. Its dark palette follows Orkavian's near-black, muted-silver, and
+restrained green-accent visual language; translucent, locally blurred panels
+keep operational content legible without turning diagnostics into decoration.
+
 ## Deliberately deferred work
 
 - TODO(gcs-live-mavlink): generated MAVLink Common plus custom-dialect