restore the code editor screen, drop the dead theme picker, unshadow AppRegistry

Three unrelated type errors that each pointed at something actually broken:

- Dashboard.CodeEditor was deleted in ab03b17 ("Projects") while the
  /code-editor route and the dock's Editor item kept pointing at it, so the
  route rendered undefined. Screen restored.

- Appearance.tsx imported 'themes', a workspace deleted in 0746844. Nothing
  reads settings.appearance.colorTheme and no theme CSS survives, so the picker
  was writing a value with no consumer. Removed it and the setting; colorMode
  stays, it is live.

- officerdev exported both a component and a type named AppRegistry, so
  `import { AppRegistry }` resolved to the type and <AppRegistry /> failed to
  typecheck. Renamed the Record type to AppRegistryMap.

Also declares "*.css" so side-effect stylesheet imports resolve.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/apps/officer-web/Screens/Dashboard/CodeEditor/index.tsx

@@ -0,0 +1,10 @@
+import { CodeEditorView } from 'officerdev';
+import { Widget } from 'widgets/Widget';
+
+export const CodeEditor = () => (
+  <div className="h-full w-full flex items-center justify-center">
+    <Widget title="Code Editor" className="h-[70vh] w-[70vw] overflow-hidden" resizable moveable>
+      <CodeEditorView className="h-full w-full" />
+    </Widget>
+  </div>
+);